Christian, thanks for showing what a 6" can deliver on Jupiter. Lots of stuff to discuss.
One question, though, in the SEB (first sketch.) The white spot should be following the darker spot, do you them backwards or notice another white spot?
Actually, it looks like yo may have actually seen the darker oval trailing BA. Now, there are some tiny, faint features down there, just as you show. There is a bit of a belt preceding the GRS. That belt is slightly north of BA. So, if you saw something behind BA that was not that belt, it has to be the darker oval. I think you may have seen it. And by the way, that belt is not easy either, yet you seemed to have captured it. Well done.
The white ovals in the second sketch indicate you had very good seeing. Well done, again. Those are delicate features, in my experience. Any breath of air and they wash away.
It's nice to know you had an awesome view, and maybe more successful than you imagined.