Hi Ricardo,
I can't do that, unfortunately. There are several reasons why I cannot update my machine to a later OSX version than El Capitan, at the moment. I did not encounter any problems so far that could be tracked down to the XCode version.
Btw, I solved the problem. For some reason, after running the Project Tool again in a fuzzy "F*** it, it has has to work!" moment, things started working. I am stumped, as I don't know the reason, but anyway, the problem's gone.
Cheers,
Frank