Unfixable on my side, everything rendered to depth buffer do cast shadows.

I think you are asking in wrong place. I never did reflex, so not know anything about it.

There are no cpu dependent effects in the enbseries. It's also impossible to have 100% cpu usage for such cpu cause of 16 cores, it's just a game, not cpu benchmark. Search problem elsewhere.

Game before "next-gen" update.

Don't remember, but big chance cause old version it do not have menu yet. Also it may not work at all, because game had many updates since the mod release for it.

Solution is to use old game version.

Files of enbseries are not properly installed, some missing or in wrong location, very common bug report.

Sorry, i quitted making anything for this game and to play it, enbseries was not popular for it.

Version updated, download again
Added subsurface scattering to latest game update. Added OLEDBandingFix parameter to the enblocal.ini by request.

Просто шейдеры бесполезно изучать, потому что большинство кодинга внутри. Просто шейдерами не реализовать эффекты. Часть конечно можно, но мало чего.