I think it is wise to find some way to test content before deploying it to the public. If you can't afford having a test server, can you not run the same build of the server locally for testing ? Either that or communicate with the players to get feedback and also discuss between staff members. Because taking the current event as an example, the outcome was obvious as an instance for level 40+ looting for level 65, 12 chests, 5 times per day, and the other one 3 chests, 16 times per day. And the fact that people with multiple characters/accounts can run it. When you release something like this out in the open suddenly, players will just think that this is how the event is supposed to be and that the administration did testing and approval before the launch. You should always think ahead and carefully before deploying anything. Now after the change, people are just gonna run Steel Rose over and over again with reset scrolls. Also there's a chance that people will start taking all the chests in level 65 instances and not letting other people get theirs.
Some suggestions for the current event :
1) Remove steel rose reset scrolls from shop temporarily for the remainder of the event.
2) Compensate by either raising the chance of the ice pick drop or add more chests. *the adding of chests is for Steel Rose, the ice pick drop chance can be general.
3) Make chests loot for everyone instead of being a unique item that one person could all take from himself. *for level 65 instances that requires group/alliance, you can decrease the number to one per person but everyone gets his chest not a unique loot.
I'm not saying THIS is what you should do. This is a discussion and other can add their own suggestions and ideas and we can reach an understanding on what's better and fair for everyone. Because saying that everyone have same conditions and that it's fair is not true since people can just buy reset scrolls and do steel rose infinitely. Before anyone could do the event since the only abuse is having multiple characters and that's basically the "fault" of the players for having only one character, not fair, not the same conditions, but understandable and it's okay. The right way would have been to decrease the number of chests on said instances that were removed. Now it's reset scrolls on the shop and that's not the fault of the players but the server and that's just seems totally not okay and p2w just like when people bought reset scrolls to get more serums, same story.