Since it doesn’t seem to be a question (request for help with PrePoMax simulation), but rather a showcase of a completed project, I moved it to Tips & Tricks. We have a Users Showcase section on our Discord server, feel free to join us there: PrePoMax & CalculiX
Regarding your model, I would just advise using hex meshes (shouldn’t be a problem with such blocky parts) and avoiding tie constraints. See this thread for some similar examples: Validation against ISO 10211-2017
Also, one of my older tutorials covers a double-pane window, but analyzed in 2D (and including hand calculations): https://www.youtube.com/watch?v=sfY5BEHUsmk