^ Nice work! The asymmetrical lieutenant j.g. seems a little odd, though. Maybe a viable alternative would be to have lieutenant retain the front piping from lieutenant commander but drop the collar piping, then have lieutenant j.g. have just the collar piping and not the front piping.
You're right, admiral is kinda tricky. Maybe you could have the piping that runs from collar to armpit be the wide piping. But I'm really not sure how you would differentiate the four different admiral grades.
Good catch on Mendez... I never clued into that. I'm guessing the real-world explanation is that they only did a commodore version in red, so when they needed another gold one, they just gave Throne one of the two gold captain's uniforms they had created for Court Martial