Should we hard-code messages that event registration cancellations are not refundable?
Self-service cancellation of event registrations does not support refunds, so there are at least two places where the registrants are told that there are no refunds (in the registration confirmation email if self-service cancellation is enabled and when they actually try to cancel, though this has been broken since 5.43).
I wonder if it makes sense for CiviCRM to put this expectation that there are no refunds into code. Even though refunds are not supported via the self-service form, organizations may have policies that are different and may manually process refunds in some cases. I think it would make more sense to simply not say anything about refunds and allow organizations to define their own policies in the event registration.
So my proposal: Remove the warning about no refunds from self-service cancellation (which doesn't currently work anyways), remove the text about no refunds from event registration confirmation templates and remove the help text that mentions no refunds from the self-service cancellation option on the event registration set up.
It's far from ideal either way, but I think leaving it open is better than specifying a policy that may not work for all.