I'm trying to update CustomObjectTranslation components with a callout to the Metadata API through Apex and I have been able to accomplish the task for my own custom objects and managed fields from standard objects. The problem is when trying to update those custom objects that come from a managed package. When list the Metadata I can see those components there, but seems like when I try to read them it doesn't returns anything, with or without namespace, I think I've tried everything.

I'm starting to think it's just not possible to read a managed CustomObjectTranslation, although I have no problem when doing the same with CustomObject or CustomField, It's just the translations from managed custom objects that I'm not able to update.
I've been searching the net without success for the last week. Hope somebody knows what I'm doing wrong or just if it can tell me that it's just not possible to do (although if that's the case retrieving that same component with a tool like Ant shouldn't work either and it does).