Reading your blog, NFITC1, it looks as though the out of battle effects are stored in a simple, 'uncompressed' fashion.
If I'm reading correctly, it would be very easy to write a secondary application that modifies this data. I suggest a second application, because the alternative is that PC becomes a 'modding suite' that deals with a mass of files - making things far more complicated than they should be.
It would be easy to adapt a pre-existing program job. It's just a matter of changing the offsets it looks at and altering labels. That is, of course, assuming the data 'lives' in an "uncompressed" form in one of the PSX modules (that is to say, there's a MENU.BIN with a nice long list of attack data for each item out of battle).
If needs be, feel free to download and modify the Libre sourcecode. I don't really mind. I wouldn't say Libre is as well written as it could be, but it is, I think, very clearly commented. And Python is very simple to understand.