Wikimedia Commons now supports localizable strings for Charts, and they can also be used for other purposes.
The strings are stored in a JSON-like file, which is different from MediaWiki's usual JSON format. All the languages are in the same file, and each message key has translation according to language codes. See https://commons.wikimedia.org/wiki/Data:Original/Template:Graphs.tab for an example.
It would be nice to support this in Translate as an FFS.
- Fuzzying when English changes.
- Validation (probably the same as MediaWiki)
- Discoverability in the message group selector