I really wished to read that series as well! But sadly where I live that series doesn't came out at all...
Well..why harsh? Have you read the story about Raidon Kane? Abolethic Sovereignity i think. He went to a town where pilgrims went to get a spellscar. Most of the died trying. So it is high risk (maybe) high reward situation. Some spellscars are useless :P
Well for me, spellscar would be an interesting addition in both way (just a graphical addition in c.c. or a high risk high reward bonus what maybe "backfire in the face") if Larian do that.
Just imagine the situation when your M.C. walk in a big city like B.G. with an unhidden spellscar (which can be backfire any minute).... That' would be a real "Roleplaying" with soo much potential!
No Githyanki would be a monk class since that's more of a Githzerai thing anyways,
Githyanki are fighters and Githzerai are monks, also with Githzerai you swap out +1 strength for +1 wisdom.
Just as you said, and it would be really easy to create them but sadly for some reason it looks like Larian doesn't want to correctify or expand the c.c.
Which is really a sad thing because even if they just copy the parameters of the old NWN2 c.c. (which would be the most correct c.c.until now, among all the games which play in Faerun) their game would be soo much greater! I know every developer team "want their own and unique" ..etc. But why change the perfectly working? BTW that was a correct one so it wouldn't be a copy, just simply another world (Faerun) correct c.c.!
And must say I'm really upset about the mistakes which have in BG3's c.c. because in one hand Larian really do a great job to implement the world and it's details, but in the other hand they don't give a damn about this mistakes which could be correctify easily without any drastical changes or hard work.