Battery Water Level - Bit above Green Line

My, my! How fancy!

I think you are okay on the very slightly overfilled battery cell, since you didn't spill any battery electrolyte while adding distilled water a few drops at a time. And you did the right thing by not allowing the electrolyte level to fall below the red line. The battery plates must be covered with electrolyte at all times to preserve the life of the battery.

As for my "how fancy" comment... my automobile battery makes it almost impossible to remove the cell covers to inspect the level of electrolyte. Car batteries don't last very long anyway, even if given tender loving care. So I never check the car battery for electrolyte level anymore. However, if someone leaves the lights on and drains the car battery, that pretty much ruins it for ever holding a decent charge again. Car batteries, unlike most UPS batteries, just aren't made to survive deep discharge cycles. So, after hooking up to a battery charger long enough to start the engine, I always plan on replacing the battery. Up north, in Dayton, Ohio, I usually was lucky to get three, maybe four, winters of service life from my car battery. My motorcycle battery was a different story. Each cell had its own cell cap, but without the fancy float mechanism that your battery sports. I had to pop the cell cap off (most are press fits) and visually inspect inside the battery to make sure electrolyte fully covered the plates. Adding distilled water can be a pita too... a medicine dropper helps, along with a strong flashlight beam. Most motorcycle battery cases are translucent, so theoretically you can check the electrolyte level without opening anything. Of course that's before road grime obscures everything.

You didn't say what your 12 V inverter application was... solar panel dc to ac conversion or UPS service... but unless you frequently discharge the battery until it is dead, it should provide many years of service. In the meantime, stay safe, avoid crowds, wear a "surgical mask" if you go out in public and allow your hair to grow longer. There will still be barbershops around after the current pandemic passes. It's better and cheaper to make your own masks, and wash them everyday after use. Visit the CDC (Center for Disease Control) website for information on how to make your own masks. Something as simple as a bandana and a pair of elastic hair ties will work. Instructions for that are also on the CDC website.

 

I agree, your fine.
It's worth noting that the water level varies depending on the charge the battery holds.

Typically you water when the battery is fully charged and you top off the cells to the full mark.
If you were to top off the water level on a discharged battery it would overflow acid when its charged.

If you want to check the water on a discharged battery, it should slightly cover the top of the plates or be above the red mark on your level indicator.