That IR receiver is classed as legacy in the datasheet. It may be that the modulated bursts are too short for it to lock on reliably or could be that its a 56kHz signal???
If you are confident opening up the receiver in the curtain unit, you could tap into the output signal, provided it is 3->5V, with your arduino and use the following sketch to record the times.
CAUTION: use at your own risk and beware of any mains voltage.
download link at bottom of page
Now that I think about it, your could use this sketch to get better timings than IRrremote, from your existing receiver- so why not try that first before messing with the curtain unit and post the output.
Regarding your Panasonic TV....this signal will work if you resend using sendRAW. You could also update the library to handle the actual codes.