I’ve ben involved with the charming community for a relatively short amount of time, so would love to hear more background related to this.
My perception is that a “shared code-base” typically becomes dominated by a single developer/team. And they’re more than happy to make changes without seeking input from other parties. From what I’ve seen, layer developers don’t see interfaces as shared or common, but a private implementation detail.
IMO introducing breaking changes to an interface would be better handled by creating another interface. But that opinion isn’t very well formed.