but you also have the issue that once depressed, the keypad sinks in rather deeply into the Pyra casing, which made me worry a bit about stuck keys - especially when combined with the tilting phenomenon so well-described by Yoyobuae above with his animation.
No, that can't happen, not even with the current travel distance.
The top of the keys currently is 1mm above the case.
Current travel distance is 1mm (but should be 0,8mm in the finished one), so right now, it reaches exactly the top of the case, and when it's finished, it should still be 0,2mm above the case.
Then you have the plastic caps that surround the keymat with a height of about 2mm (don't know it exactly out of my head, but that's an estimation).
The case plastic surrounds these caps with a height of about 1mm.
This gives the keys both stability and also makes sure they can't get stuck.
So, let's think about it:
The keys are 1mm above the case, which means about 1mm of the plastic caps are surrounded by the case.
If you press down the key, the plastic cap will sink into the case (1mm right now, 0.8mm ideally when they're fixed) and the height of the surrounding it 1mm.
To get them stuck, you need to push the keys AT LEAST below the surrounding of the case. So the travel distance would need to be at least 2mm before that can happen... that's twice of the travel distance we have right now.
So nope, they can't get stuck. Not a chance.