yeah the documentation states "I was thinking the user could try a few other tools to convert the wav to something else lossless, and then back to wav to see if it helped, might get lucky with the right header (and a working file).
--no-convvag Don't automatically convert WAV sounds to VAG format
(based on extension). Note WAV->VAG conversion is lossy!
"
So I am guessing the converter is just badly written?