Watch it only will be telling after most of the damage is done...
Hottest point/area and is where the heat is generated...is in the TC and at the edges of the vanes
ATF temp senors are normally NOT there, but elsewhere in the tranny assembly. Where the ultimate temp is no longer, but muted by thermal mass and fluid dilution. That is part of the heat rejection management system...which is the main engine radiator and maybe an external Aux ATF cooler
The damage will be in nibbles over time/miles. Initially not noticeable and will be an ever increasing issue
By the time the temp is noticeable...already too late and maybe watch it fail out in the boonies somewhere
Not just temp of the ATF, but the ATF's ability to lube the various parts well...as the temp increases up to the ATF OEM's max temp spec...its ability to lube is less and less until there isn't enough lube specification to do the job. By overloading, the engineered margins are reduced...meaning that most folks do NOT know that proper gear lube is engineered to have a layer/film of lube between mating gear teeth...and a ditto for bearings. They are NOT supposed to go metal to metal when the ATF and the rest of the gear box is used within spec...
Have no skin in my advice provided...just have to sleep at night...rarely say 'no'...just provide info for the OPs to make up their own risk management decision(s)...AKA gambling...