Yes you must propagate Cathedral from a rhizome to get a new Cathedral. If you do it by leaf you will get an ordinary beefsteak or something similar.

There are many plants that behave like this in the plant kingdom. For instance thare are many variegated plants that can be propagated from a cutting and keep the same variegation but then there are some variegated plants that will just revert to their normal green parentage unless you start a new plant from the rhizome or base. Sansevierias are like this. Species can keep their color by leaf cutting but variegated ones must be started from an offset to keep their parents' coloring.

Fiji Islands is just a smaller version of Cathedral but you won't get a Fiji Islands from a Cathedral through propagation. You might get a bonsai Cathedral if you limit its growing space.

Thanks very very much for the information on Cathedral Begonia propagation. This forum is a great way of sharing information... Keep up the good work and thanks again for taking the time to help me better understand a Cathedral.