Maybe because no one ever thought to turn towards the corresponding Sanskrit equivalent; namely:
pratītya-sam-ut-pāda (as in SF 163).

Note that "ignorance"(avijja) is the starting point of it all, (and that (complete) knowledge (vijja) is the ultimate goal).

¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦
Paṭicca = pratītya
¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦

First, let see what pratītya is all about.

Pratītya is the future passive participle of "pratī".
Future passive participle are translated as "to be xxxxed" .
So let see what pratī means, in the pre and contemporary literature around Buddha's time.

प्रतीत्य pratītya [fpp. pratī]

प्रती pratī [prati-√ इ i ]
- to come back, return RV. ;
- to resort or apply to RV. AV. ŚBr. ;
- to admit, recognize, be certain of GṛŚrS.
- known, understood, implicit Pāṇ.
- to be admitted or recognized Śaṃk. ~
- to make clear, prove Śaṃk. ~
- Desid. [ pratīṣiṣati ], to wish or try to understand Pāṇ.


प्रति prati [ práti ] ind. ( as a prefix to roots and their derivative nouns and other nouns, sometimes [ pratī ].
- towards, near to.


√ इ i
pf. (ati, adhi, anu, antar, apa, abhi, ava, ā, ut, upa, ni, parā, pari, pra, prati, vi, sam)

- to go , walk ; to flow ; to blow ; to advance , spread , get about ; to go to or towards ( with acc.) , come RV. AV. ŚBr. MBh.
- to go away , escape , pass , retire RV. AV. ŚBr.
- to arise from , come from RV. ChUp.
- to return ( in this sense only fut.) MBh.
- to arrive at , reach , obtain RV. AV. ŚBr.
- to appear , be KaṭhUp.
- to appear , make one's appearance RV. AV. BṛĀrUp.

Pass. [ ī́yate ] , to be asked or requested RV.


So as a past passive participle, we would have such ("Sanskrito-English") translations as:
1. prati-√ इ i
------------------
- to be returned - towards to.
- to be flown, to be spread, (to be gone towards) - towards to.
- to be gone away (passed) - towards to.
- to be arisen from - towards to.
- to be obtained - towards to.
- to be "appeared" - towards to.



2. pratī(tya)
-----------------
- "to be come back (at), to be returned (to)" RV.
- "to be resorted or to be applied to" RV. AV. ŚBr.
- "to be admited, to be recognized, to be (made) certain of" GṛŚrS.
- "to be known, to be understood, to be (made) implicit" Pāṇ.
- ~ "to be admitted or to be recognized" Śaṃk. ~
- ~ "to be made clear, to be proven" Śaṃk. ~


For instance, the first pratī's definition (viz. "to be come back , to be returned" RV.) can be found in the following (as a karma retribution):

Today Sīha the general has slain a plump animal to prepare a meal for the ascetic Gotama! The ascetic Gotama knowingly uses meat obtained from an animal killed especially for his sake, a deed that will come back at him (viz. to be returned to him).
Ajja sīhena senāpatinā thūlaṃ pasuṃ vadhitvā samaṇassa gotamassa bhattaṃ kataṃ. Taṃ samaṇo gotamo jānaṃ uddissakataṃ maṃsaṃ paribhuñjati paṭiccakamman”ti.
AN 8.12

The second definitions (namely, "to be resorted" [viz. to proceed towards], "to be flown towards") have to do with the arising and fading (perishing), as we will see below.

And the third definitions (namely, "to be obtained - towards to" (vijja) - "to be admited, to be recognized, to be (made) certain of" - "to be known, to be understood, to be (made) implicit" - have to do with the knowledge (vijja) acquired through "actualization" (the universal philosophical notion of actual VS potential).


¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦
Samuppāda = samutpāda
¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦

One should break up paṭiccasamupāda & paṭicasamupanna in their constituent parts (e.g. roots).

Uppāda [Sk. ud + pad]
patica + sam + ud + pad.

::::::::::::::::::::
उद् ud
:::::::::::::::::::::
to flow or issue out RV. AV. ŚBr. KātyŚr.

::::::::::::::::::::
पद् pad
::::::::::::::::::::
- to fall, fall down or out, perish RV. AV. VS. Br.
- to cause to fall AV. AitBr.


-------------

उत्पद् utpad [ ut-√ pad = ud-√ pad ]
- to arise, rise, originate, be born or produced ; to come forth, become visible, appear ; to be ready ŚBr. MBh. Mn.
- to produce, beget, generate ; to cause, effect ; to cause to issue or come forth, bring forward MBh. Mn.

--------------

समुत्पाद samutpāda [act. samutpād]

समुत्पाद् samutpād [***causative*** of samutpad]

समुत्पद् samutpad [ sam-ut-√ pad ] - (pp. samutpanna)
- to spring up together , be brought forth or born of (loc.) , arise , appear , occur , take place , happen MBh.
- to cause to arise , produce , effect , cause MBh.

उत्पद् utpad [ut-pad] - pp. (utpanna)
- to arise , rise , originate , be born or produced ; to come forth , become visible , appear ; to be ready ŚBr. MBh. Mn.
- to cause , effect ; to cause to issue or come forth , bring forward MBh. Mn.

√ उद् ud (ut)
to flow or issue out RV. AV. ŚBr. KātyŚr.

√ पद् pad
- to fall, fall down or out, perish RV. AV. VS. Br.
- to cause to fall AV. AitBr.

√ पद् pad - pp. (panna)
- aller, marcher
- tomber.

सम् sam
- together


¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦
CHINESE
¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦

Paṭicca-samuppāda

Usually written as:
緣起: to arise on a condition.

Also written as:

緣生: produced by causal condition.

因緣生: generated from causes and conditions

With:
緣: condition
起: to arise
因: a cause (nidāna)
生: arising



|||||||||||||||||||||¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦
(Paṭicca -) Sam - uppanna = (pratītya -) sam-utpanna
¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦

Samutappana = समुत्पन्न samutpanna

“So, householder, whatever has been brought into being, is fabricated, willed, and sprung together (viz. the khandhas) to appear - that is impermanent /not yours (both are the definitions of anicca). Whatever is impermanent/not yours is stress. You thus adhere to that very stress, and submit yourself to that very stress.”

“Venerable sirs, whatever has been brought into being, is fabricated, willed, and sprung together (viz. the khandhas) to appear - that is impermanent/not yours. Whatever is impermanent/not yours is stress. Whatever is stress is not me, is not what I am, is not my self. Having seen this well with right discernment as it actually is present, I also discern the higher escape from it as it actually is present.”


“Yaṃ kho, gahapati, kiñci bhūtaṃ saṅkhataṃ cetayitaṃ paṭic­ca­samup­pannaṃ tadaniccaṃ. Yadaniccaṃ taṃ dukkhaṃ. Yaṃ dukkhaṃ tadeva tvaṃ, gahapati, allīno, tadeva tvaṃ, gahapati, ajjhupagato”ti.

“Yaṃ kho, bhante, kiñci bhūtaṃ saṅkhataṃ cetayitaṃ paṭic­ca­samup­pannaṃ tadaniccaṃ. Yadaniccaṃ taṃ dukkhaṃ. ‘Yaṃ dukkhaṃ taṃ netaṃ mama, nesohamasmi, nameso attā’ti—evametaṃ yathābhūtaṃ sammappaññāya sudiṭṭhaṃ. Tassa ca uttari nissaraṇaṃ yathābhūtaṃ pajānāmī”ti.
AN 10.93

Pali:
Uppanna, [pp．of uppajjati]

Sanskrit:
panna m. n. pannā
Past Passive Participle


समुत्पन्न samutpanna [ sam-utpanna - [pp. samutpad] ]
- sprung up together, arisen, produced, begotten by (abl.) or on (loc.), occurred, happened, taken place Mn. MBh.

उत्पन्न utpanna [ ut-panna ]
- arisen, born, produced Mn.

पन्न panna
- fallen, fallen down, gone.

_________________

Also:

¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦
Paccaya, [Ved．pratyaya]
¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦

प्रत्यय pratyaya [act. pratī - see above] .
- ground , basis , motive or cause of anything MBh. (no pre or contemporary Buddhist's reference; afaik).
- proof, ascertainment Mn. MBh.


________________


CONCLUSION:

If Paṭicca-samuppāda & Paṭicca-samuppana have anything to do with Paccaya & Sankhata, the latter two words do not seem to include their meanings in the strict definition of the former two. Indeed the "cause" is found in samutpād, the causative of the "active" samutpad.
And if samuppāda is the "active-causative" (what causes) ; samuppana is the "passive-"effected"" (what has been produced").

Paṭicca-Samuppāda means:
What springs together [flows out & perishes] (samuppāda/samutpāda), to (appear and) be understood (paṭicca/pratītya).
&
Paṭicca-Samuppanna means:
What has sprung together [flown out & perished] (samuppanna/samutpanna), to (appear and) be understood (paṭicca/pratītya).

_________

NOTES

Note on the side that SN12. 20/ SA 296 / SF163 are very poor parallels.

. 

------------

SN 12.20 & SA 296

What are the differences between the two texts that can highlight the meaning of both terms?

Paṭiccasamupāda
----------------
First, paṭiccasamupāda is given in reverse order in both texts. SN 12.20 starts with Existence, while SA 296 starts with Ignorance.
The order does not seem to matter. What counts is the fact that the dependent arising (paṭiccasamupāda) is a natural and immutable Law.

Common to both texts is that:
It's a fact of nature (persistent) (ṭhitāva sā dhātu) - there is a constancy (stableness) of phenomena (dhammaṭṭhitatā) - a certainty (fixed course) of phenomena (dhammaniyāmatā) - it is suchness (tathatā), not unsuchness (avitathatā), not otherwise (anaññathtā)

 

     _________

*