HAL said he’ll be providing the lossless audio in PCM format as a W64 file (as WAV has a file size limit). If you open the MKV in either mkvtoolnix or tsmuxer, you can add the W64 file and create a new MKV or a BDMV folder with the lossless PCM audio instead of (or in addition to) the Dolby Digital audio.
As for the other part, I can’t get any of HAL’s projects to burn to a Blu-Ray disc and play without errors in my PS4. Other people have had similar issues, but none of the proposed solutions have worked for me. I’m hopeful that the fact that I now have a standalone player (not a game console) will fix the problem for me.