Hi everyone,
As with my last problem with the handmaiden solved itself in way, i just found the next one.
I went to Korriban as the last planet and let Kreia teach me about the graves and then went to the academy before visiting the cave.
In the Academy, I had the problem that when I picked up Vash's remains I got a conversation error and I couldn't use her code to unlock the doors.
I solved that problem with using the English Dialog.tlk. then I fought with Sion explored cave and grave.
My problem now is I still have the traces to ashes quest active telling me to search the academy. The quest Lost Jedi which tells me i found her remains that she was held as a bait.
My guess is the switch to English messed up the traces to ashes quest although i had to to that to go on.
I use TSLRCM and the following mods
Coruscant Scene No Overlay by Hassat Hunter
Player & Party Underwear 1 by RedRob41
Concept Loading Screens 1.1 by InSidious
New Onderon Merchant by 90SK
edit: removed "TSLRCM Loot fix base scripts 1.3 by Hassat Hunter", forgot i uninstalled that one