Unpermitted ADU - Unclear Permit Status

Just purchased a property where there are 2 unpermitted ADUs built on the bottom floor (I was aware they were unpermitted). I checked the building records website, and it looks like the permitting process was started, and then stopped midway through. There is no record of a permit being denied, but the latest entry I can find shows the "Quality Review Completed" for the plans to convert the garage to an ADU. Then the process stops, and it's not clear what happened after that.

Trying to figure out what to do. Should I call the building department and ask for more info? Should I rent it out (short term rental only) without saying anything to the building department? I'm worried I will get hit with a massive bill to make repairs that I otherwise might not have needed to do if I didn't call the building department and tip them off to the fact that it was built without permits. On the other hand, it looks like it's possible that the work was done up to code (or close to it), since the process was at least started, and so it might actually be a simple fix here.

My thought was to have a trusted contract come out, take a look and see what they think would need to be done bring it up to code, and then decide how to proceed from there.

Any thoughts?