Think you could give a quick explanation of how to get the cheat engine working? I'm a noob with it and I can't quite find the right address.
The biggest factor that's probably setting you back is that CE defaults to looking for 4 byte values, while GameMaker games tend to use doubles. (For GameMaker games in general, it's usually helpful to go to edit -> settings -> scan settings -> and tick the "all type contains..." double + 8 bytes so you can scan for both at the same time with "all," but just searching for a double works here)
Starting the game, scanning for a double with value 0, grabbing the first treasure, scanning for any that have updated to value 1, and grabbing the second treasure + scanning for 2 should narrow it down enough that you can try changing values and backtracking to the chest. You can grab the third treasure while backtracking if you're careful about avoiding the water droplets/vines to be totally sure, too!