I can confirm Capella is built differently than Capella Studio, Capella 6 works in my 1.8 java environement, whereas Capella Studio does not!
I have 2 type of environements, in one of them I don’t even have access to the local path (really), so in best cases I will be able to make it work only half of the time.
Anyway, This does not incite me to move from capella 5 to 6 at all. Maybe I could use some of the workarounds you shared after investigating some potential solutions.