Also not really unbalanced with the sleep thing, in fact that is actually working as intended. Sleep is a common low level spell, it is a saving throw that your party can pass, and Elves and certain other character types have advantage on certain saving throws and immunity to sleep. In a casting system where slots are limited, something like sleep is reasonable. Especially since it is likely to be resisted, the elf can be punished to remove concentration, and if anything happens to your party will awaken them, not to mention the fact that it affects a certain health amount so at a higher level of level 3, you will definitely have party members who are not affected because she can not upcast it.
I don't remember exactly how it's been changed in BG3, but RAW Sleep doesn't allow a save and isn't concentration. Creatures with summed HP up to 5d8 just fall asleep (unless they're immune). Sleep is a very powerful spell against low-HP enemies.
But as you said, yes any damage or being shaken awake automatically wakes them, and it only affects 25ish HP so will become ~irrelevant past level 3 or 4. In BG3, I've heard that enemies wake up after a few turns, indicating that they're probably (incorrectly) getting STs each turn to wake up.
