Interesting take on a swerve drive. Using drive units separate from the main modules used to be a norm, but now people like to place the two closer together to save space. I would recommend that in your case, as your swerve is currently quite large and has a lot of unnecessary shafting.
I really don't like crash shifting.
Your gear mesh is highly dependent on how accurately your cylinder/linkage move, not to mention the huge gear tooth stresses from having two different-speed gears mesh. What's wrong with just using a ballshifter/dogshifter, or no shifter at all? Any of those will reduce weight and footprint, not to mention complexity.
That being said, I like the way you've set up the gearbox. All the positive shaft retention everywhere is nice too.
Your caster box/module looks really solid, except for the washer on the horizontal bevel gear. Washers are not accurate in thickness, and in your case it also looks like it might rub the outer race of the bearing.
Why are you cutting away so much of the large turning gear?
I think your encoder stage should be fine, as long as you do the right math to convert it to true angle.
LOVE the wires and chains in CAD. looks very nifty.
And lastly: what made you choose this design over a bevel-beside-wheel swerve? For the amount of machining you're doing, that might end up a lot more compact and lighter for you.