I finally get it. So much for needing help.
Basically, the reason why it looks like those XMLs only replace a few things is because there's no need to specify most replacements. Most of them get taken care of by (for example) Hozu's <folder external="/private/wii/app/RSBE/shared/" disc="/" />, which takes all files and folders you've got in /shared, and swaps them for the analogous files in the root of the disc. The reason why
any of them are listed specifically is because the code assumes people have been removing the _en from a lot of their files because the file patch code demanded it, and those lines are just a fallback in case the replacement of them didn't work from the <folder external="/private/wii/app/RSBE/pf/" disc="/" /> line. At least, I assume they're just a fallback. If you
do have a FitCaptain01_en.pcs, it should be properly swapped by <folder external="/private/wii/app/RSBE/pf/" disc="/" /> and you won't need <file external="/private/wii/app/RSBE/shared/fighter/captain/FitCaptain01.pcs" disc="/fighter/captain/FitCaptain01_en.pcs"/>.
About that last example, though, I'd like to point out that Hozu's code won't replace the .pac for FitCaptain01 unless _en is in the filename! There should be a <file external="/private/wii/app/RSBE/shared/fighter/captain/FitCaptain01.pac" disc="/fighter/captain/FitCaptain01_en.pac"/> in there, too.
Anyway, it looks like there's really no need for me to release any new XML. The one I'm making for myself is just a stripped-down version of Hozu's that fixes the FitCaptain01.pac problem and removes all the mod support (since I only play regular Brawl).
All problems solved. Thanks for the
help.