He doesn't appear, to me, to have glucose toxicity and what you are observing isn't uncommon. I've seen it in other cats. It's possible that when he got a little green, he "might" have had better absorption that day.
What makes it a little difficult for me, in making a suggestion, is that you aren't doing TR with the caveats you have. It might be better to change your signature block to read "individual dosing; do not copy" or to actually do TR as it is written.
I don't understand what the recommendation is based upon that you hold for three drops below 70 or hold the dose if nadirs are below 150. I think what would help him most is if you can try to do either TR or SLGS consistently because the current approach is not working.
If he doesn't hold reductions and you are going to do TR, then let him go between 40-50 three times before you reduce.
If he were my cat, I wouldn't get attached to a dose or worry that he might have to go up higher than he's been before. I would increase his dose as long as you can monitor.