During my last EasyTUTU-games I noticed that Shar-Teel always joined the party with 2.150 XP regardless of the much higher XP level of my party or PC. To test this assumption I created a new PC, gave myself immediately the maximum of 161.000 XP and recruited her - again 2.150 XP. Actually, there should be two other versions of Shar-Teel with 8.213 and 32.590 XP (source:
http://www.dudleyville.com/bg1/evil.htm ). I'm not sure if EasyTUTU is to blame, since I have the "ToB-Style NPCs"-component from BG2 Tweak Pack v1 installed, another potential source of the problem.