How many languages can the PV750 support?

I tried removing Italian and Czech and added a couple of new ones
The User Settings:Italian:SystemText[USA Standard] for Italian was still there in the Strings that I exported.

Can you clarify. Did you remove the languages from selected languages or the available languages. Language strings are not deleted until you remove them from the available list and therefore can be exported.

There is no real set limit to the number of languages supported. However each one takes memory and storage space so in practice limiting it to a minimum number needed is best for performance and space..