I get why many users want an edit feature, but I don’t want to implement something that’s essentially self-deceptive. Users should be clearly aware that once something is signed, it’s immutable.

An "edit" in practice is just publishing another event that says what you changed. Not all clients support this, and I’m worried users might assume everyone only sees the edited version. I think adding clarifications via replies is a better approach, since that’s visible to everyone across all clients.