The story of Triskel is quite charming! As for why a three-legged cat can't play the piano, there's actually no reason why they couldn't, at least to some degree.
 
While a three-legged cat might face some challenges with piano playing compared to their four-legged counterparts, they could potentially adapt. Cats are remarkably resilient and can adjust to having three legs quite well for most activities.
 
For piano playing specifically:
- If missing a front leg, they'd have one less paw for the keys, limiting their range
- If missing a back leg, balance on the piano bench might be trickier
- They might need a specially adapted instrument or technique
 
But with the right setup and perhaps some creative accommodations, a determined three-legged cat could certainly produce some music! There are many examples of animals with disabilities accomplishing remarkable things when given the opportunity.
 
In the spirit of your story, perhaps Triskel could surprise the villagers with an unexpected musical talent, challenging their assumptions about limitations!