Ah, bummer. Much thanks for trying. I know VOX.DAT doesn't seem to be compressed as they can be played with a correct header/genh IIRC (I think this is where the sample data is also, can't quite remember). DEMO.DAT is where I found all of those KDT's for reference. Thanks again for trying.
Just wanted to drop by and let everyone know I fixed a syntax mistake which could have prevented Silent Hill 2 and other more recent games to convert. Please follow the project on Github from here on for updates, as I've decided to delete the script from my Dropbox.
In Suikoden II, the KDT1 data is in the .SDD files. You would just need to remove the first 40 (0x28) bytes from the SDD files to be able to convert with kdt-tool. You can use a hex editor (e.g. HxD) to do this.