Nearata yes, that's because the raw reason attribute from the database is used as the {reason} attribute in the translation in addFlagsToPosts
We should probably have a map from database value to label, like in FlagPostModal. I think we might have to switch the translation based on the reason there because just translating {reason} will create problems in some languages.
Are you able to create an issue for this on GitHub so we don't forget about it?