I just playtested that part of 8-4 castle on FCEUX v. 2.2.2, VirtualNES v. .89, and Nestopia v. 1.40 and didn't have any problems accessing the part of the castle after the water area. I don't understand what's preventing you from finishing the game.
The original ROM I used was the GoodNES (Super Mario Bros. (W)[!].nes), so I don't see how that could be the issue if you used the patch on the very ROM I created the patch from. This is very puzzling.
I'm glad that you've been able to play my other hacks without any issue and enjoyed them.
I just wish I could figure out how to prevent the bug you're experiencing, but I cannot seem to replicate it to solve the issue. Is it possible you could somehow make a video of you experiencing this glitch or try downloading FCEUX? I really want to try to find out how to fix this issue.