Battle Events not working?

Hi, I need some help with events that are meant to happen at story points in battle. Dialogue itself in battle proceeds normally, but it's the sprite animations that take issue.

For example, the whole affair with Biggs, Wesge and Terra in battle with Whelk, and the incident at Tritoch. During the Whelk battle, Biggs and Wedge jump around a bit and do their hoo-haa, but for whatever reason their sprites do no animating at all when using this rom. Then when Terra is supposed to walk up to Tritoch before the MagiTek armor explodes, she doesn't move. In fact, Biggs and Wedge simply don't disappear, and the blue light and explosion occur in the middle of the screen with Terra in the entirely wrong place, simply not having moved at all. What I miss most is Locke and Edgar's emoting during their discussion of "MMMMMMAGIC?!" the first time they both see Terra use it.

It's things like that all throughout the game that are the problem.

I'm not entirely sure what caused the problem. I've tried a couple of patches on my FF6 rom recently, and made some sprite changes with FF3usME67, but I've tested those changes again on a freshly download rom, and no problem seems to have occured on it. I CAN just decide to play a new rom, but the thing is I've already made a lot of the changes to the aforementioned rom that's been having problems in battle. Many item changes, dialogue, sprite edits, patches, etc. To do that all over again would take a very long time. For the sake of convenience, does anyone think they know a possible solution?