I have seen quite a few Youtuber's presentations, obviously you can always find those who knew what they were talking about, sadly, many (seems a larger proportion) didn't. Yet I have no doubt to most people who watched them would have been convinced that they did know what they talked about.
I have tried using the mini in as many combinations as I could think about, and in my experience, for EQ, it made little difference whether I did it before or after, or not using it at all. I only have two subs that need time alignment though. For EQ, in theory at least Audyssey would be better because it uses FIR filters, and XT32 obviously have higher resolutions where as the mini, used with REW is limited, and the filters are basically PEQs, just like YPAO's. For time aligning multiple subs (more than 2), people find it a must, but since I don't need that feature so I have no experience with that. You results obviously indicate it is doing a good job for you.
All these are academic and fun to do, as you said early, audibly speaking you don't need a visually stunning flat curve to sound better. As you know I have the bragging for having some FR curves 20 to 200 Hz within +/- 1.5 dB or +/- less than 1 dB for 18 to about 125 Hz after hours of tweaking with the App, compared to the virgin unmolested curve post audyssey's +/- 5 dB, I cannot honesty say one sounded better than the other and for sure cannot tell a difference if subjected to a DBT.
By the way, expert or not, you obviously done some extensive research in all these, and now have some great curves to show, so I hope in future, you will post to help answer questions related to XT32 SubEQ HT and minidsp questions.