I mashed at 152. I'm getting my target FG from Beersmith. The sample didn't taste overly sweet to me so I guess that's what matters the most.
I relied on the kit instructions for the amount of yeast to pitch. Next time I'll check Mr Malty.
I did aerate by stirring with a wisk. I probably could of done a better job with aeration.
Would US-05 be a good idea to bring the FG down or is it better just to call this one done when I get a steady reading?
If T-58 was pitched into wort and finished up at 1.020, there's no reason to think that US-05 is going to do any better in an environment that has a lot more alcohol and a lot less O2 and sugar. It's generally not worth it to pitch a new yeast unless there's some reason to think your yeast kicked the bucket way too early and the wort is still pretty sweet and low in alcohol.
If you really want to give it a shot, then your best chance for success is to pitch a starter at high krausen of a yeast that is both attenuative and alcohol tolerant. WLP099 is an option. WY3711 could work in a Belgian beer, but that may backfire and drive your FG all the way down to the mid single-digits.
You could also go the long route and pitch Brett, then sit on it for another year or two. That has the potential to yield fantastic results.
TL;DR - if it doesn't taste horribly underattenuated you're better off leaving it alone