Concerning Sirene in EET
Looking at continuous SireneNPC again, it may be a valid idea to make the choice of additional classes in BG1 available only for non-EET games. This can be done by the mod itself or (interim) in BWS.
I assume that the options were introduced in the original BG1 mod without (at that time) considering that they would carry over to the BG2 part with EET. Those choices are not available for the BG2 mod and may not be compatible with the later mod contents.