Part of the power equation is distance from the speakers as well as your volume level. Is that -12 as setup/calibrated by YPAO? I didn't look up the spec on those speakers for my brief post before but from what I remember they're middling sensitivity-wise (mid 80s IIRC) and can have some low impedance swings so the speakers present not the easiest load for a typical lower end avr's amp section. If it's not tripping the avr's shutdown function it's probably fine, tho a little extra help on cooling would be a good way to go, especially if in a cabinet or rack that retains heat. Got a thermometer gun in the kitchen/garage you can get some measurements of the temp at the case? I'd probably not be worried too much and hopefully that smell goes away after a bit? The radiating heat at 6ft I hope is an exaggeration, tho.
If you do want to calculate some idea of your power load let's check out the speaker spec. Sensitivity is 85 dB (2.83V/1m). Say you sit 9ft away from the speakers, and using this handy dandy
spl calculator and ignoring boundaries that 30w for just your L/R/C speakers would yield 96 dB at your seat. If watching a movie that's following the standards that would be roughly -9 on your volume dial (considering reference or 0 is average levels of 85 dB with allowance for peaks to 105dB). I usually don't listen to mine that loud, I'm more at -20 myself most of the time. So your estimate of 30wpc at -12 is in the ball park if you sit at approx 9ft from the mains. If you sit closer then a little less stress on the amp, if further away then more strain on the amp.