Such obsession..
There is no "perfect" battery, every one will have cells which will vary how much water is used slightly, at the end of the day, 1/2 ounce is peanuts.
I don't dote or obsess over my batteries, I only check them ONCE A YR, typically in the spring before we start camping. This yr due to the virus, we didn't camp.. So, I didn't bother checking the water..
Recently decided to check to make sure TT is ready for winter I checked the water..
Took about 2 ounces per cell for a yr and half sitting on charge with my PD9160 with Charge Wizard.. I do not directly measure exactly how much water I added to each cell, I use store bought 16 oz bottles of water.. This yr only used ONE 16oz bottle over all six cells.. I add only enough to get close to the fill ring.
In my case, top of the plates were not exposed and that SHOULD be what you are concerned about.
Replaced my last set of GC2s at the 9 yr mark and they were using average of 4 ounces per cell (TWO 16 oz water bottles)and not holding as good of a charge as I wanted.
As long as you have a decent charging setup which drops to 13.2V your batteries will not use much water.
Your batteries are fine, don't sweat slight differences in water consumption, just don't allow the water to drop below the top of the plates and you are good to go for a long time.
