Adding this here for posterity's sake: the game starts up just fine with the d3d8 frontend (as-is) backported to dxvk 1.10.3 levels, so the crash is actually a regression in the d9vk/dxvk backend. Things used to be more accommodating when it came to UAF, at least.
Since the game was also working just before the d8vk merge into dxvk, at least with the workarounds I added for it, I expect it was some change done around that time that caused it.
The game seems to work fine on Wine Staging 10.7, might have been "fixed" a while back actually. Video playback (the original reported issue) no longer flickers either, so I guess it will never get any better as far as this game is concerned. Random crashes may still happen, but that's just how the game is even on Windows. Future breakage may still be an option, but nothing dxvk can affect in any reasonable way.
The use-after-free the game relies on seems to be (again) broken on master, though I have seen times when it does work, as if by magic, after which it will refuse to start on the next 50 attempts. In any case, it's still a problem (though also a known game bug for sure).
Again appears to be fine on more recent Wine releases, at least I haven't been able to get it to crash at all now. Needs the LAA flag to be even remotely stable, and it can still crash at times, but that's just how the game is. No point to keep this one open.
The game crashes on startup with dxvk 2.4, although it used to work with latest d8vk master. I suspect the crashes are caused by: https://bugs.winehq.org/show_bug.cgi?id=32235 , namely the game relying on use-after-free in certain places.
Besides that (when it works) 3D rendering looks good, however game intro videos and campaign intro videos flicker (this doesn't happen with WineD3D). The flickering seems to occur because the game is using multiple swapchains whenever video playback is involved.
Software information
Soldiers: Heroes of World War II (GOG)
System information
Apitrace file(s)
Soldiers.trace.tar.xz
Log files