How to use different entity info per entity bundle? I have three specific vocabularies that reside on different URIs and I need to have the Field UI configuration available for those URIs instead of only at one specific URI.

How could I configure this? The entity info is cached so alteration would not yeald the required result.

Bundle info only allows altering the label and some other unimportant value at this time.

This should basically act just like the entity uri override done by Forum module(although I think this is still not implemented yet).

Edit:
As I have mentioned I have three vocabularies A, B and C. I have three routes for each of those vocabularies and in there I am calling the Drupal\taxonomy\Form\OverviewTerms form with vocabulary argument which is the name of the vocabualry that I want to display.

This gives me the vocabulary term list overivew. Now I want to add the vocabualry edit form as local task on those paths which I still can do(manually).

The issue is that I would also like to have the Field UI(ie. manage fields, manage form display, manage display) available at those routes/paths. And this is problematic since the field ui route is defined in the vocabulary entity annotation and is universal for all vocabularies.

The only way I think I can do this is by somehow duplicating what \Drupal\field_ui\Plugin\Derivative\FieldUiLocalTask does but I was hoping for more simpler way by just having a different per-bundle information.

For more context/information see https://www.drupal.org/node/2460207
I don't really understand what you are asking, but it's not possibly to have different entity type definitions per bundle. The only exeption is the uri callback, that forum.module is using, as you mentioned yourself.

As I said, I don't understand/you don't explain what you're actually trying to achieve. Try to explain that, maybe there's a way to achieve your goal, just not in the way you imagined it.