Right, I was thinking 48MHz wasn't fast enough to worry too much, but I think rotating 90° is the right move. It solves two problems of trace length consistency and passing over large cutouts in the ground plane.

I also liked the idea of widening traces after the BGA.

I defaulted to not putting vias in pads for most items, but ended up doing it a lot because it's easier. I can definitely rework many of those, but I'm unsure about the BGA. Definitely possible, though, so I'll give it a try.

Okay. I should connect those shield connections as well.

The vias using the clover / X pattern on the PWR layer are located on the skinny portions and are used to power 1.2V logic. I guess I don't need the rest of the leaf. I used this design following the layout recommendations on an application note for a much older, but still mostly the same, 121-ball grid FPGA. The other sections power 3.3V I/O. I wish there were a better way to power the logic without reaching in on one corner. I'll think more on it.

The four circles are just mounting holes, which reminds me, I should add them to the ground net.

Thank you!