My reply to that comment would be stored on the programming.dev instance though, right? (I've been meaning to look into how this all works and the ActivityPub protocol.)
I think it will first be written in your instance's reflection of that community and later the original instance will pull the update. But I'm not 100% sure.
Yeah I also havent looked into the backend much yet but I assume at some point while creating it would still try to connect to kbin before it posts in programming.dev to make sure its valid
Happened to me earlier for the first time. I tried a bunch of times and gave up. It sucks cause I was kinda proud of my comment, but I wrote it about 5 times so now I know it.