I don't know if honda v6 is known for causing varnish or sludge buildup
we owned a 2007 honda civic with the 1.8L R18 something engine, on Walmart and random oil change place cheapest dino 5w20, it looked exactly the same as your engine at 180k when I changed the valve cover, and it got maintenance minder from 15% to 0% for intervals. I could be wrong but aren't Honda engines very easy on oil, to begin with? you used full synthetic oils, which could have easily gone 10k unless Honda V6 is known to varnish and sludge.
Also, did you change the valve cover gasket so you could look inside or because it was leaking, from my understanding, wouldn't FS oils make the valve cover gasket last longer? My 2GR-FE V6 with FS oil on 10-14k OCI under my care doesn't have any sign of any leaks.
Mobil 1 0w20, Mobil 1 EP x2, and the last oil change was Napa FS 0w20.