Apparently Crohn’s appears different from say Pouchitis.
There is no test that magically and reliably distinguishes between Crohn's, pouchitis, or "new disease process", which is what modern researchers think chronic inflammation appearing in and above J pouches may be. In my case they chased expensive and inconclusive diagnostic tests for a few years, and then gave up, deciding effective treatment is more important for the inflammation than what to call it. The latest/newest development is that they believe it's a new disease process and not Crohn's, but it really doesn't matter since you have what you have and still need to treat it.
In addition, guess what? All the potential treatments are the same, regardless of the name or label.
In your case it seems like a number of biologics can still be attempted- Entyvio, Stelara, Humira. Entyvio has a way different mechanism of action than Remicade and is often indicated as a second line biological option. Good luck