Thanks for your insights, really appreciate any kind of feedback! 
And yes, you’re absolutely about the reverb problem in some passages. Some instruments definitely didn’t get enough (e.g. the piano and synth piano in the final track: “Resolution and End Credits”). Must have missed that in the mastering.
Anyway, the film itself has finally been uploaded on youtube:
SARAH - Thriller Short Film [German/English Subtitles] - YouTube