okay, finally got a chance to take a closer look. when i unpack the inistaz file, i get the initistay.big file. unpack it and i get this:
as you can see the files are named by the directory. you actuall should try this - we'll use the bat.fsh file as an example. as you can see, it's been unpacked and named "models[slash]textures[slash]bat". well unpack that fsh with nfshtool and edit the bats to whatever you want. then repack it to "bat.fsh" not "models[slash]textures[slash]bat". then install that bat.fsh file with kraw's installer. see if that works.
the only other thing i could possible see that you might have done wrong besides editing something you shouldn't have is that using the installer thingy create a new big file, it saves it to your mvp folder. meaning, once you've unpacked everything and edited it, you must first create the inistay file, which will end up in your mvp folder. take that and then create the inistaz file. again that will end up in your mvp folder. move it over to where it needs to be and see if it works then. otherwise, i'm kinda stumped in all of this.