All have the same problem on soundbar systems (and likely also on surround receivers).
I just don't get why these particular games generate hdmi sound that gets wrecked by so many setups, one would think there was a way to fix this at the source - the generation of sound on the pi/other device.
Just my 0.02 here, the world of modern TVs and home theater/surround sound devices is needlessly complicated for these simple old tasks we are trying to recreate here with simple digital signals (ironically that are emulations of old analog signals).
What I would try to see if it helps:
Many TVs have a "game mode" that is intended to reduce or eliminate "signal processing" to enable a more pure, delay free signal and timings. Many surround sound receivers have something similar, although it is usually called Pure Audio or Direct Sound mode. You might see if your receiver has this option and try it to see if it eliminates audio hitches.
For what it's worth, I have an Onkyo receiver at home and even with modern consoles I have noticed that something in the HDMI convergence where all video inputs are routed to a single HDMI output to the TV will cause a 'gap' in sounds sometimes. (After a dead silence of any kind, the first sound made is either dropped entirely or gets cut so I only hear part of it before normal audio resumes. Sort of like the audio stream has to buffer up before it becomes stable again.)
EDIT: Hit the submit button too soon and wasn't done typing.