Why start off by being condescending? I'm legit trying to learn.
I've understood the concept from the start; it's not that complicated. I'm not disagreeing or confused with any part of how the upgrade system works, just the cap on TH gear.
Devs have said that TH+ from gear and traits caps at 8. You are saying otherwise. Everything you're basing your replies on assumes that the TH8 cap only applies to the starting point but is bypassed for upgrade procs.
From your own link at
https://ffxiclopedia.fandom.com/wiki/Treasure_Hunter
Also at bg
https://ffxiclopedia.fandom.com/wiki/Treasure_Hunter
Neither source makes any reference to procs bypassing this cap. Neither of them use example numbers for using anything beyond +8. From the start, I've been asking you where this cap bypass information came from.