Here’s a suggestion/beg for mercy.
Can we have an option other than “sell” on a cover, where it will then give us a new random cover of that Star tier?
For the sake of argument, 5 CP for a 4* and 10 CP for a 5*. Maybe 1 CP for a 3* so players at the lower tier can re-roll something they aren’t ready to Champion yet.
This gives us options other than feeling terrible, while sticking with the randomised evolution of a roster that makes it YOUR individual roster.
Your re-roll can need re-rolling again, and the greedy can burn all their CP throwing away covers they could use but they are trying to hit one specific one, but these are likely just a bonus feature from a money making perspective 
It also wouldn’t be too code intensive to add, like the requests for colourless covers.
But please implement SOMETHING to help with the ongoing dumpster fire of redundant covers X_X