It still sounds wrapped up in jokes. Frisk isn't going to expect anything, not for real. They're good with the piano and singing, but the playing needs improvement and their voice can still be strange sometimes if they don't do enough.

...besides, some people won't want to listen to a Chara sing, unfair as that would be.

They move on; just gotta keep playing along with the joke. "Sure! We should charge home cooking, too, 'stead of money."