deafult_repo.xml contains repo information, it should not be translated. If you want to translate repo names and descriptions, that information should go in the index, not the client.
mmm I tried to find them in "Not translated", since they are appearing in English in my (Spanish) F-Droid client.
Now I see them, translated, in the translation system. Are there two issues then?
One about the missing "Weekly" and "Every 2 Weeks"
Another one about, at least, Spanish translations not arriving the /res/values-es/arrays.xml file...
AFAIK arrays have temporarily stopped working since we are using a newer version of the translatewiki script to pull translations. Reassigning to @CiaranG.