Right, so the neck pocket itself isn't square either? That's not great, and I can't say I've seen that problem before.

I'd probably be talking to Adam (Pitbull Guitars owner) at this point, but it's going to be tricky with you in France and the current global situation. I would shoot him an email and see what he thinks/suggests, he's very helpful.

Looking at your diagram, and if its accurate, I would be attempting option two of levelling the neck heel so its parallel to the fretboard. The angles on the side don't matter as much. But before you do anything discuss it with Adam.

Unfortunate you've had this issue, but it's not unfixable and there is nearly always something that needs a bit of tinkering to get right, so don't get discouraged.