@michael - If you’re only seeing duplicate presses, then yes, more aggressive debouncing is a solution that should work for you. Updated attiny keyscanner firmware that does more aggressive debouncing is something you can find in git, though a build is here:
Inside, there’s an Arduino sketch you flash to your keyboard. It will then flash the keyscanners. (Output will be send to serial.)
Once it’s done, you’d just flash your keyboard firmware again.
Newer Matias switches (those used from MP3 forward) used a different lubricant, which dramatically reduces chatter. But a switch you’ve cleaned should be about the same on that front.
In terms of why we’re using MX style switches on the Atreus: Since we picked the Matias ALPS switches for the Model 01, the switch market has matured a whole bunch. Kailh and Gateron both offer high-quality switches with many, many different options for force curves, none of which were really there when we had to lock in the design of the Model 01. On top of that, the Atreus is designed to support hot-swap, which isn’t available for ALPS-style switches at this point.