I'm honest: I can't follow you.
The point is: I've got a bilingual website with two designs, one related to each language. (French and German, German as default). Only registred members can access and they choose their default language.
This generally works for all Joomla-content (every menu item exists once for each language and picks the template for the respective language).
But when you use a CB-funcitonnality, it falls back to the default template, so it's the wrong one for the french users.
I hope to have been clear.
Thanks again
B