Mausi

- all RAS kits (for example M1 to M1 RAS) state that the stock should be detached before conversion: the stock can't be detached

Yes, the descriptions need to be updated. Not sure if the new "replaceable" setting will cause problems so I'll need to test these kits for actual function as well.

Mausi

- Trigger Group is a permanent attachment, but doesn't pop-up the "are you sure" message when getting attached

I don't think I've noticed this, can you replicate in stock v1.13?

Mausi

- the AK 10X series (i guess all of them, however i had only the AK 107 so far) accept Trigger Groups, resulting in a 6 shot burst
maybe this applies to the bullpups as well

That's a bug, probably have the wrong (N)CAP for trigger attachments set for the 107

Mausi

- Galil Sniper accepts Trigger Group: the burst hast the same AP costs as Single Shot, the vertical/horizontal recoil stays at 0.0

Same bug, see previous.

E1vS

Scar L 47 CQC kit sold in Assault rifles section at Bobby Ray shop.

Yes the SCAR kits, like AR Uppers and AUG barrels are classified as guns. Also yes SBR/CQC Assault Rifles are still Assault Rifles.