You went for such great lengths, that's much appreciated!
What is a a0e9010fb0449dc9d824b5978ee759eeaf50f7c6 here - some checksum? I took the file from https://github.com/praydog/REFramework-nightly/releases/tag/nightly-01391-a0e9010fb0449dc9d824b5978ee759eeaf50f7c6 - and SHA-256 is 10792e2b1141c4c0e135141da5d92b281a334cea0ff9fcc3f3e482cf2df8d00f
So, I have a voices38 version of Pragmata as well (played before installing REFramework; will try to reinstall if nothing else helps), I downloaded REF Nightly 01391, I moved dinput8.dll into the game folder, and added Pragmata executable as a non-Steam game on Steam. Then I've set the launch parameters as you've mentioned, and used Proton-GE Latest as a compatibility tool (Also tried regular Proton 11). When launching the game, the window for REFramework showing an initializing status (see screenshot) appears, and after a few seconds, the game freezes completely.

P.S. Reinstalled the game (downloaded another source) and have put the DLL before first launch, still no luck there. Same issue persists. Also, tried to load the game without it and disable frame generation. Didn't help, either.
System: Fedora running on first-gen Ryzen and a Pascal Nvidia card.