So based on that, I chucked together a quick, kludgy SPR extraction tool. For the most part, it works well, although it does have issues with a few graphics... not really any of the important ones, but it'd still be nice to iron these out.
EDIT: Fixed! Forgot to account for (or rather, didn't notice due to hasty reading) the special treatment of 0x7F for the offset.
EDIT: Okay, tested with a few files and I think I've ironed out the issues. In case anyone else wants the tool, it's
here, Delphi source code included. If it can't autodetect the palette file (and it is
not very smart at doing this), it will ask you to select it; if no specific one exists, generally, FE.PAL should be used.
Output files are 32-bit BMP files. This is not a widely-used format (but I was a bit too lazy to implement PNG support); but most programs that can handle BMP should be able to load it, and the fancier ones should be able to handle the transparency as well (Paint.NET can, if you need a free app that does; it can't save 32-bit BMPs as far as I can tell, but it can load them, including transparency).