Ok, so having added an ALERT_LOG call in the sound_play() function in lisaem_wx.cpp, I'm seeing output in the log that it's trying to play sounds, however there's some issue where it doesn't actually play the sound.
So this is a LisaEm bug. Turning on the RETARDED_SOUND definition makes it work most of the time for freq parameters 400-2200 on Linux. This should, but doesn't work on macos, not sure why.
(Note about the define RETARDED_SOUND is a define that composes a wav file and writes it to /tmp then plays it. The alternative is to compose the wav in memory and tell wxWidgets to play it that way which is better. But not great as it has to be in the proper format so there's a lot of gymnastics to create the file and then play it. There's no way to just give it a buffer with a waveform without the .wav header.)
At some point this code was ofc working.
Some days I really hate wxWidgets.