Need screenshots. Also multiple weather system do not produce bugs.

Doesn't matter, backward compatible.

Use old game version, before that "next-gen" update or don't use enbseries. To fix such bugs i need to spend lot of time to find conditions when they occur to be able see myself, so chance is very low it can be fixed without help

Then try old version of the game, before it was updated few years ago. Or try new vegas (it was not updated) and if it still not works, then something is wrong with crapware or missing directx libraries as i told earlier.

I can't help. After game update i don't know what is going on with it. It could be windows 11 incompatibility too (maybe changing game properties to win7 compatibility would work then, hell knows).

Hard to say. If i remember, game was updated few years ago and it may not be compatible any more. But crash is abnormal behavior, even if incompatible, so it is rather something wrong with missing directx libraries (need old version, from summer 2010). Or some "crapware" is running on back...

ENBSeries creates editor windows, menus, so on. But it doesn't mean all of the items there are made by me. There are enb sdk addons and skse plugins which can add new things to the enbs editor or even add new windows of it. Tthis is out of my control and knowledge, only author of such addons/plugins...

So what? Anybody can add new menu item anywhere.

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.