The fun of events is the unexpected content.

Writing ideas here in public might already be a spoiler for them...

Would the developers (especially the Settings and GM teams) prefer an anonymous way to submit suggestions?

Some of the ideas here are very good, but I agree with LigH that this isn't the right place to put up your thoughts as events are meant to be unexpected. If you know the result and way to do an event, it is no fun. Posting here will only make your brilliant ideas worthless as there will be very less chance that the GM/Settings team will do an event about which the citizen know. I would advice you to write the event script nicely, and send it to a GM.

Or are they already certain that they don't need any suggestions, because they are brilliant enough for the next years? (No offense - just one question among several.)

We are constantly doing work on a newer event and we always welcome suggestions from players, and now I will surely be waiting for some suggestions from you.