Look at it positively,
you won four times even though you think you're not great at the challenges, four wins is pretty good considering five is pretty much the limit with old account malus (you can get 6 if you start on hoeing but then you just get 4 the next day unless you go for an extra loop), so you're better than you think at these things.
Getting a dupe key always stings a little bit, or a lot if its for a good game you wanted, but yougot it for free so its not like you lost anything, its just annoying.
Winning
MINING with 16 malus? Are you sure about that one? Archer is doable, just extra challenging, but when you win a 16 malus archer challenge... HMMMMMM thats a sweet victory!

At least for me, this is the only challenge that I Iike winning at the 16 malus limit probably because of the hard time I had getting used to it from the beggining, watering I think is also possible but that one is just "
Yeah you gotta do it pixel perfect or you lose haha", but when it comes to "malus limit" challenges its really just play the one you WANT to beat at its possible limit because that will be the one that you'll enjoy beating the most.
Hoeing is also possible at 20 malus if you do it with no error, my notes say 4 missclick limit but that may also depend on getting a good map for it and I only tried it once or twice so I might be wrong... I should try this one again...