I have basically done everything you did here. Skimmer with a recirculating co2 scrubber, large refugium opposite my lights, and I know have a 55 gallon tank full of kalk dripping as much as I can to match evaporation.
I am not overly concerned with it, but my ph is not stable like yours. Around a .26 daily difference.
So there are several factors that contribute to CO2 levels in the tank and I can't quite control all of them. As my photosynthetic organisms have grown, my daily pH rise has also increased, and I've mostly given up controlling the highs. I would need fairly high (600+) indoor air CO2 and probably an even larger skimmer to compensate with.
My typical swings are now roughly between 8.18 and 8.28 with my setup and natural home CO2 levels. The 2 big factors are kids are now in college and household is half the size (6 to 3) and my house has lower CO2 in the colder and milder months. It's hard to drive down pH when my indoor CO2 levels have been mostly below 500ppm.
Natural reefs have something less than a 0.1 Total pH swing.
Post in thread 'Alkalinity stability? pH stability? Are they even different?' https://www.reef2reef.com/threads/a...y-are-they-even-different.711768/post-9382573
In terms of coral growth, I agree that elevated pH is great...BRS has some good evidence of this. However, I now have things that are growing too fast. As I'm not a coral farmer and I plan on keeping my tank for at least 8 more years...speed of growth isn't really desired.