Seems there's a bug with the "Construct 1x Level 1 Main Stage" quest for the event. I constructed it and got a note that said I could delete it afterwards, so I hit the button to trash it, but I can't claim the quest as completed (not sure if because I hit the trash button, even if it hasn't been deleted yet).
There really should be a button to cancel the deletion or construction of a building if it is still in progress. I'm stuck having to wait 15minutes for it to delete, only so I can waste resources rebuilding it (for another 15min) to complete the quest, and that's not devastating in the beginning but later buildings take longer and are costlier.
Not getting topaz during events is a huge bummer too, there should be a warning for that when spending it (not simply the "are you sure you want to spend this rare currency?"), since the "Can afford in 1d05h" you get after running out is super misleading; one might only realize afterwards that in fact you won't be generating it at all during the event... which is unfortunate given how sparse events already are.
Doesn't help that indicators such as land (left) and etc are kind of unclear and you might end up building tiles that you can't actually use to place the buildings you planned to (specially considering that by quest #14 I only got 2 free unlocks).