Good detail, nice selection of links showing good research, good testing of Rx/Tx with the other library.
There can’t be much wrong with most of it as the console is getting, processing & accepting the join-request.
The first question that comes to mind is how close is the device to the TTIG - they need a good few metres & possibly a brick wall - too close and the signal can overwhelm the input stages of the chip scrambling the signal.