Hi,
nice to know there are other people working on improving the game (besides the packmakers, of course)
At this point, adding a building/job requires (significant) changes to the C++ code of the game.
What is far easier is to edit the scripts, which are written in lua and don't require you to recompile the game. For example, in `Training.lua` you could add a "Send her to the gym" option. Not quite the same as a new building with new jobs, but a starting point.
The files in `Resources/Data/Jobs` also make it possible to add different text variations to job, e.g. to take into account your new traits. It does not currently work for all the job text in the game, and it cannot be used to add new jobs, though.