I see your point but since they all implement interface StringBridge it should not be too confusing,

It is. If you look at written code, you don't see neither the implementation details not the javadocs. Sure, once you dig deeper it becomes clear, but descriptive names would remove this ambiguity from the beginning.

while renaming would create a lot of integration work having zero value for the end users. It doesn't seem worth it?

It has value. Code is easier to understand and maintain (for the user) . Also migration cost for the user is minimal. I would expect that only very few would reference this bridges directly. So far there was really no reason for that. Now, however, we need the user in some cases to differentiate (eg during faceting). Names become more important.

I think I'll would go for a rename.