Sorry, I didn't recall that you had posted pictures of your room. I am not sure how 7-channel stereo would measure, but it is not the recommended way of measuring. When using REW to find the best spot to position the subs, you should turn off all other speakers and measure only the subs. Find the best spot for the first sub, then the next best spot for the second sub, and then measure both subs and optimize their interaction. Finally, to assess the overall bass performance, measure either Left+Right+Subs, or Center+Subs, or both. Since all speakers are (or should be) set to small, and the crossovers are at least 80 Hz, it is unlikely that the surrounds are contributing much bass to the measurement below 100Hz.
My understanding is that YPAO doesn't equalize the bass region, so as I said earlier, the 818 might/should smooth out the bass response. Your main issues are peaks at 32 and 50Hz, and room correction is better at handling peaks than dips.