Alrighty, just uploaded a new version that ought to give some messages to let you know when it doesn't like something, and should provide some kind of output even when it fails.
The problem stems from this program mainly being a raw structure issue diagnoser and formatter that I sorta shoehorned into a stonesense graphics converter, and as such there isn't much in the way of raw argument error processing. DF complains about that stuff itself like 99% of the time, so I just never bothered with it. As such, while the tag name (0th argument) does generate errors if it is unrecognized, the rest of the arguments weren't set up to. The version I just uploaded should
mostly fix that, though I'm sure there are creative ways still to confuse it.
The first kind of error was coming from lines like this:
[MILITIA_CAPTAIN:1:4:AS_IS:DEFAULT]and is a result of a missing TILE_PAGE specifier. Adding a TILE_PAGE (eg: PUTNAM_TROLLS) fixes this.
The second kind of error stems from including a TILE_PAGE name, but not having that tile page defined
in the file. Simply copying the tile page specifier to the top of the file with the others should fix anything like this.
Hope that helps