Im not suggesting that the text to be translated should be posted to instances. That would break the right to privacy.

However, I think a fediverse could improve such offline tools that you are referencing as well improve translation tools that has access to the internet.

This could for example be done by having instances specifically designed to create dictionaries through collaboration, perhaps with a very specific theme. An instance could have an aim for creating definitions in mathematics, for children or for carpenters. A dictionary could then be generated from a set of instances.

These definitions could be designed to allow for automation of translation. Perhaps through use of functional definitions.