Some adventures have ridiculous requirements. I was doing one the other day and for the life of me could not get gold (requires you to complete the adventure in 1:20). It was the race in AuB. NO ONE had gold. NO ONE was even on the leaderboard for more than bronze. I’ve been finding some of the challenges too easy (i.e. the one with tendrils in VB) and some nearly impossible to get gold (i.e. the first one in AuB, and the race one I mentioned where you take on the form of a mushroom).
I hope sincerely, you will review the criteria for achieving gold in these and change them accordingly.