Problems translating the default "Name" field on tags
I can confirm this is indeed the case (as of  2.1.2564). I don't know if it's intended behaviour or a bug, but I would wager the former.  I seem to recall somewhere learning that P&amp;T made an explicit decision to not have tag Names be translatable.

As a workaround you could consider a tag custom field with a "translatable label" that you fill in for each language? Seems a bit lame. I'd probably opt for simply making the field itself translatable, and then binding separate tags for each language.