We encourage people to practice, maybe with a used syringe, on drawing up those tiny doses until you can do it fairly consistently. It doesn't matter if your 0.25u is the same as someone else's 0.25u. What matters is that you can reduce from the 0.5u you've been shooting and that you can replicate the dose again.
The reason that people are encouraging you to try a smaller dose that you can give twice a day is that Lantus only lasts about 12 hours in a cat's body. For some cats it's as little as 8 hrs. If you're only shooting once a day that leave a lot of hours without any insulin helping keep his blood sugar controlled.
That said, he does look pretty good and even his morning numbers aren't bad. They still are hovering on the border of normal/diabetic though. Everything under 120 is considered normal, although for remission to stick most of the time the cat needs to be under 100 for most all of their tests.
It doesn't look like he'll need insulin very long but I'd encourage you to give him some for as long as he needs it, until his blood sugar is under 100 and staying there.
You say with the TR, you shoot anything above 50. That would make me extremely nervous and I'm not sure I want to go out on that ledge. Judging by Baby's drops at +3-+6' I would not want to shoot at any lower than probably 130. Yesterday, with no shot, he even dropped slighty at +2.
The way Lantus works is that when a person shoots a lower number, the blood sugar doesn't necessarily drop. Shooting a 60 might mean that for the next 12 hours the cat stays around 60. When you shoot a higher number, even 150, there will likely be a drop in the middle of the cycle. That's simply not true in a cat that's nearing OTJ. It's logical to apply what you have experienced at a higher number to a lower number, but that's not how Lantus works. Take a look at
this thread, where it's discussed a little more thoroughly, and especially look at the spreadsheets that are linked for you to see how it does work.
With a kitty out of remission, typically you have to be more aggressive with dosing to get them back in remission and especially, to have it "stick" this time. I'd try to give 0.25u twice a day without skipping any shots if I were you. Of course that means you have to check him in the pm cycle, but if your goal is to get him back in remission and have him stay there, that's probably your best chance. He may be able to hold these 115ish number for a while without insulin, but that's not the same as giving his pancrease enough support to let it heal, go into remission again, and then for him to stay diet-controlled.