Sometime after 2021.32 and I think in 2022.12 the following was added to the manual about TACC:
“With Traffic-Aware Cruise Control engaged and cruising at a set speed, you can also change the cruising speed to the current speed limit (including any offset you've specified), by either pushing the drive stalk downward and briefly holding, or touching and briefly holding the speed limit sign on the touchscreen, until you see the cruising speed change.”
I believe the stalk functionality is a useful addition that I've not seen in any release notes. Touching the speed limit on the screen already worked.
It means you can set TACC to initiate at your current speed and then change to the speed limit with the stalk at any time, presumably whenever the speed limit changes.