The method presented by Chris would need additional consideration. If the default value is changed, then it would no longer match the "cached" value in the database, and by this logic, Composr would believe the config option is not supposed to be default (and thus would use the old value). We could implement a clearing out when a language string is changed, but this would only work for options which use language strings as defaults. This would not work if, say, an integer's default value changed in the hook.

We should also consider if we want this behaviour in the first place for non-lang-string config options.

Changing the reporter to Adam even though I made the issue... Adam made the original issue which prompted this issue (5604). And I'm assigning him as reporter so he gets proper credit on the logs for inspiring this.