The Special:Export API should [be able to] export data using the canonical namespace names. This way XML export could be directly imported to a wiki installation configured with a different language.

Currently there is additional two steps required:

1. Change the target wiki's language to match the source (this step could be eliminated using the suggested fix)
2. Import XML data
3. Revert the language back to your desired (this step could be eliminated using the suggested fix)

See related issue T159401#3935518 which workarounds this way.