The cipher decoder system doesn't really bother me so much. I can continue playing through activities that aren't the Haunted Forest to grind for keys that will open up chests within runs through there. However, this unfortunately means I'm instead not spending time participating in the event. Grinding for keys instead of grinding for opportunities to go after loot is not exactly ideal.
Another thing is that the Haunted Forest is entirely despicable. Why is there a modification system at play, a giant knight that hunts players, or unobtainable rewards if you happen to fall down at the end of your run? I'd much rather spend as little time as possible venturing through these woods than hack my way through the Infinite Failure.
Yeah, the self-respawn handling in the HF is beyond stupid. Another reason, on top of crap loot and stupid cipher decoder requirement, to not even bother.