I got some feedback that the original Hatari MIDI Mapper from 2021 did not work for old Sierra games (for example Police Quest 2) when enabled to play on the MT-32. Many thanks to Eugene B for the testing and feedback!
I investigated the issue and found out that I did a silly mistake handling MIDI System Exclusive messages and as the Sierra games starts to send a bunch of SysEx messages to the MT-32, probably to set up sounds etc, the connection between Hatari and the Hatari MIDI Mapper crashed.
I fixed it and have now uploaded a new version of the Hatari MIDI Mapper in the downloads area: HatariMidiMapper1.002.
As the Hatari version used for the MIDI input/output to Hatari MIDI Mapper is based on Hatari 2.4.0 and the 2.4.1 was released August 2022, I might recompile a Hatari 2.4.1 with my MIDI hooks for Hatari MIDI Mapper if there is interest for it. But I also know that the Hatari developers are working hard on a next release that doesn't look to be that far off, so I might hold off until then...