I had the battery and battery tray out and I noticed there is a drain hole in the battery tray. Makes sense. When I pulled the tray out of the car I see it drains any battery acid onto the transmission, just next to where one of the big wire harnesses comes out of the trans. There is a lot of corrosion here due to battery acid dripping out. Wondering how concerned I should be about this causing an expensive failure down the road. I could easily rivet on a little deflector/gutter to keep the acid off the trans.

I am using the correct battery for the car, it is vented on the left side with a tube that is unobstructed (I double checked) that directs any overflow down to the ground.

Also this is not new, I've noticed it for years so it isn't a suddenly leaky battery. I just became concerned today when I looked at while checking resistance from some of those wires to the Trans Control Unit.

 

That looks nasty. A battery should not leak to start with...
Clean off the debris with an old vacuum cleaner.
Using a water pressure cleaner might be tempting, but there is always the danger of spraying water into a corner, where the X-Type really does not like it, and it will cause problems - especially, if that is now "corrosive" water (mixed with that acid-dirt). So maybe clean with air pressure next and then maybe polish with a wire brush on a drill - and then maybe even rust converter and paint.

I guess there is no space to add a tube to that drainage hole and to guide that acid around the tranny? If so, make sure it cannot be caught in a drive belt.

On the right side of your second picture you can see the ground-connect-cable. Remove it and clean that contact and best spray CRC 2.26 on it.

 

Clean, then spray some Fluid Film all over the drip area.