I think I figured out why Orca didn't find BRLTTY. I did not pass PYTHON=/usr/bin/python3 to the BRLTTY configure script, so the brlapi python bindings were built with Python 2.7. Probably the same thing happened with Liblouis. Having said that, is there a way to build just the brlapi python bindings or do I have to rebuild the whole BRLTTY package?