Hahaha! I consider your exploits a huge compliment.
The challenge for "Get exactly 100 gold" is indeed bugged. It SHOULD have given you the win after you dropped the coin, but it ... doesn't? I'm working on that right now actually.
And you're in luck! I actually plan on dropping an update today. I'm not 100% sure if it'll be on itch because it makes some changes to saved data, and ... uh, I'm not sure how that's gonna interact. The only way to try out the new changes might be to reset, but I don't want to force people to do that. But we'll see.
I see that you joined the discord, though, so you'll definitely get to try the new version wherever I end up putting it. I'm so glad you've liked it!