Could you describe what you attempted to do exactly with KSE? I didn't quite catch your meaning when you said you were "trying to load NPC's". Were you attempting to change the appearance of your main PC to appear like another NPC (ie. Bastila)? If so, you may find that you will have to edit heads.2da using KotOR Tool to add a backup head for Bastila.
From KSE-readme.txt (quoting T7Nowhere, a pioneer in .2da editing):
Originally Posted by kse-readme.txt
Originally Posted by T7Nowhere, first post, page 5 of this thread
I know how to fix the head problem, but it will take a bit of work.
The thing about it. Bioware set it up so that you can't encounter an npc with your
head, so in appearance.2da there is a normalhead and backup head columns.
SO in order for and npc not to loose there head that npc would need an backup head.
As Juhani is a unique npc she doen not have a backup and when you transition from
one area to another the game checks appearance.2da(I suspect) and since your
character comes first the game will give you juhani's head and she looses hers.
There is a way to remedy this and it is simple open up appearance.2da with KT (if
you have that file in override then open that appeance.2da) go to row 8 which is
Party_NPC_Juhani and scroll ove until you see columns "normalhead" & "backuphead"
and simple type 5 in the backuphead column save the file back to override. And now
you and Juhani can be twins. if you would like juhani to have a different head when
you take hers then simply open heads.2da to find an appropriate female head (or
male. what ever make you happy) and type that number in the backuphead column and
save appearance to override.
In your case you'd want to do that for Bastila, not Juhani.
The presence of TSL doesn't affect how you edit KotOR or vice versa.
(Welcome to the forums! and don't fear, once you look at the files that KotOR Tool exposes, 2da editing will begin to make more sense.)