Don't split ground.
If you need polarity protection, put it on +12V.
Needs transient protection as well, say SMAJ18A from GND to +12V.
Needs a bit more ground stitching around the middle: observe the negative space around traces, see how they cut slots into the ground pour. Avoid traces in the same place top and bottom, so ground can be stitched over/under them. Minimize area of trace crossings, and stitch around them.
The high density vias around power components aren't necessary. I'd use... probably 4 x 20 mil i.d. vias in those locations? And probably 6-8 x 12 mil vias for the power pads on the switches, with a few 20 mil vias outside the pad.
If you must split ground, at least use common mode filters between ground domains, or preferably level translation, or even full isolators. Consider if voltage appears across the split (which is the point of doing it, after all, you're intentionally inviting a potential difference): logic levels to devices on one side or the other will be violated, or even ratings exceeded if the voltage is enough.
Tim