I have a catholic friend from many years ago who have decided to become a Jew. She is a now a jewish minister and has invited me to attend the Friday service. Am I condoning this switch by attending this service?
Attending a non-Catholic or non-Christian service for occasional social reasons is not considered problematic.
I don’t think you’d be condoning her conversion by accepting her invitation. In fact, it might help facilitate good conversation for the two of you.