I’d like to add that any Latin Catholic is absolutely free to visit any Eastern Catholic Church which is in full communion with the See of Peter and which uses leavened bread, and receive Our Lord in Holy Communion with absolutely no concerns with regard to validity or licitness.
Same goes for Eastern Catholics whose sui iuris Church uses leavened bread - they are absolutely free to receive the unleavened Host of the Latin Church. Again, no concerns regarding validity or licitness.