This is a stop gap. If there is known leg length differential, addressing that properly is not a matter just "getting the saddle height right." So to speak. Doing that can certainly get one by...but back to the OP's original question. Yes, in a case where leg length difference is known, and changing from one bike to another with a different (enough to matter) riding position, and different pedal system (with known different stack height), a new fit is recommended.

Internet experts can certainly offer their opinions, it's why Bikeforums exists, just so long as everyone involved understands that they are just opinions, and short of a fit, are at best short term solutions.