after your current discovery of the gory details, you might want to consider calling the station on it. better yet send them a post card!
They might not even know there is a problem, if you can provide the stations manager/engineer a picture of the problem. It's usually enough to light a fire under their arse to correct the deficiency. Many stations are looking for an edge in the market, properly tuned equipment goes a long way to improving the experience and their bottom line.
Even a 1st gen USRP is worlds more advanced then the diagnostic tools available when most radios stations were in their construction stages.
I applaud your efforts to write a better decoder! of the little bit of research I have done about RDS and HD radio here in the US. Both are phase locked and cycle specific to the pilot oscillator.
If you are going to continue your efforts, I am going to ask that you Please also write an encoder.
who knows maybe it will lead to better station equipment!