You're lucky, a few people have been kicked from the game immediately after using 2x coupons and lost the coupon and the buff. But hey it isn't costing Nexon money so they're not going to be in a rush to fix it.
The fact they're fixing them lets you know the bugs would've cost them money if they left them in. Plenty of bugs still floating around that won't get fixed any time soon just because they don't stop people from spending thousands of dollars on cubes and random boxes to make numbers get bigger.
Coding something from scratch and using duct tape and super glue to fuse a decade old game with decade old data together with completely new code for everything are very different things and no amount of experience or testing can prepare you for the metric ton of bugs that comes with doing that. Especially when you can only test it locally. Probably not very cost effective for them to set up a PTR, either. All you can do in this situation is hope for the best and prepare for the worst.
