Well, the EF database is meant to be used only in the context of EF, and in EF, you need to use the EF LCIA method, therefore, strictly speaking:
Can you please tell me if its ok to modify the elementary flows address from the EF database in order to match those of the OpenLCA LCIA methods?
No, this is not ok (following the license).
This is of course not our decision but decision of the EC, but should be followed.
Best wishes,
Andreas