okay, that patch looks to duplicate Bank C2's portion of the FF3us v1.1 bugfix. however, as
http://archive.is/vyM0K describes, FF3us v1.1 actually has fixes in TWO places: Bank C1 and Bank C2. with only the latter changes, you've limited a pointer from holding various garbage values to just holding FFFFh. however, there's still nothing in place in C1 to
recognize the FFFFh and treat it as a special case. now, if the arbitrary values pointed to in Garbage-Land don't trigger any bad behavior, you can get away with a half-fix ... as i did for 12 years.

things were pretty safe on a mostly vanilla FF3us 1.0, but i'd unknowingly been relying on dumb luck (until Novalia Spirit pointed out the shortfall). should Garbage-Land
be edited, as tends to happen on romhacks, a benignly incomplete patch can suddenly start producing actual, consequential manifestations of the Sketch Bug.
thus, to be complete, you'd want to fix Bank C1 as well. just Bank C2 is better than nothing, i spose, but it has risks.