only translate name.default when translation is same source and source_id

[missinglink]

The middleware/changeLanguage.js code is a little too liberal when replacing the name.default with a translation. Prior to this PR the code replaces name.default without first checking the source and source_id.

note: I struggled a bit to read and write this code, requires a second set of 👀

[orangejulius]

I think we talked about this the other day, but can you provide some more details and background here regarding the issue at hand, maybe some test cases, etc? It will be good to have for reference in the future.