Greetings Stefan,
-I have to relay how profound your program is for training and how generous you are to offer it.
I think it beats ChessBase and ChessAssistent (for training) with no qualifications whatsoever.
-My suggestion ,or question if the program has the capability, is, is or would it be possible to move the position labels in the position list up or down relative to the other labels in order to group similar positions (themes/ideas) toghether. For example, say you have a sub-repertoire with tactical positions and you have several Double Attack positions. After them you have several Pin positions and you add a Double Attack position after them. Could you move the new labeled position up the list to be grouped with the other Double Attack positions? If not then that is my suggestion.