First of all, just to put this into perspective, you can be proud of yourself for reaching this point, especially primarily with self-study. You are playing better than most adult beginners I've seen, and the effort shows. While it's true that most people on this site can play better, this place has a very high concentration of professional pianists and shouldn't be your benchmark. Starting at 32 with memory problems as you've said, this is quite impressive. Your technique isn't bad, either, as far as I can tell.
I spent five minutes trying out the section. It's mostly arpeggios, and if you boil it down, the limiting factor is, of course, the fact that you can not play arpeggios at that speed. So, just practice with your right hand. You'll be able to add in the left hand when the time comes.
You are playing it fluently at this tempo. My suggestion would be to post a video of your right hand arpeggios at a speed which is at tempo, or at least 90% of tempo. There are two things you need for arpeggio speed, as I see it -- one is the finger independence to move the fingers quickly for each group of 3, and the other is being able to transition fast. Usually, the limiting factor is the latter.
In order to practice that, you will want to practice leaping very quickly, with minimal extraneous movement (i.e. largely horizontal without too much vertical movement), from the 1 to the 3/4 descending, and 3/4 to the 1 ascending. Additionally, you would want to land on the target note and play it fluidly without an accent which is something I'm still working on.
Another thing I'd suggest is to just place your hands on a block chord, but not play it, and then immediately jump to the next block, but again, don't play it, just position your hands. I find this to be very good for proprioception and muscle memory.
This is very similar to quantum's block chord method, and you can do both. I feel like this may be more relevant to you, however, since I sort of see that you aren't jumping off the thumb quick enough. On the other hand, you do seem to have the muscle memory for the hand positions as far as I can tell.
As I said, your progress isn't bad compared to a lot of adult beginners I've seen, so don't beat yourself up too much!