and thats the problem. you did not advertise that they were not at a fixed iv rate. which goes back to my point, the buyers have been mislead. you cant expect the community to know everything you know, when the only thing theyve ever seen is shinies with 28-32 iv rate.
if it had been advertised as such, that these shinies bought from the token store, is not up to the caught in game standard, you would be right, and there would be no reason to complain.
however there was no representation of these facts, the players have been mislead, money has been wasted, and now people are unhappy.
the simple solution would be:
replace darcia, thychiz, and whoever else have obtained these faulty shinies, with level 5 versions of the same shiny with fixed rates. and then update the token store warning to include that the pokemon do not get set IV's.
the bolded is if you have set your mind to the idea you dont want token store shinies to have set ivs. if you dont, then you can change it so token store shinies get the the uber stats as well. otherwise, a warning is necessary. because with that warning, players will have no right to complain if and when they get one, and everyone will have the whole facts.