Event cheat codes

I'll admit that I don't play much of AoE2, but I was pretty bummed out after finding out that I missed two cheat codes from last event. Cheat codes are basically a gameplay feature and locking them behind a limited time challenge that could be missed for various reasons is quite mean (just think, for example, of those who buy the game after such events).

Since I don't want to just complain, here's my suggestion: I'm fine if these features are added as unlockable in these events with easy challenges, thus rewarding people who participate in those events, but after that make them still unlockable with MUCH HARDER/LONGER challenges available indefinitely (like win 100 games or something like that). I read the requirements of the event challenges and it's obvious that they are meant to be unlocked, so it's not like they are intended to be a great achievement.