I was recently reading about Isaac the Syrian. I learned that he is considered a Saint in the Eastern Catholic Church (EC), but, it seems, not in the Latin Catholic Church (LC). He is not listed here, and he does not have a YES in this list either. Actually, from the latter, you can see that a lot of saints in the EC are not saints in the LC, and vice versa.
So, if this is really the case, why is it? I could imagine this disparity does not mean disagreement about the merits of sainthood, but rather a type of specific tradition or relevance to the respective church. In effect, many LC-only saints were "members" of the now called LC (for example, Rose of Lima, from Peru), whereas many EC-only saints were "members" of the now called Orthodox Church (for example, Clement of Ohrid, from now Bulgaria).