Just found something weird while fooling around with the R/L glitch for passing through the floor. When you begin a new game and directly use it on at the tree to the left of where you spawn, there is a hidden gold coins when falling through the floor.
Not sure about the game in general, but at least in this spot I have gotten various ammounts of gold depending on what frame I decide to start to float through the floor. The ranges I've gooten in a very small test period is 1 - 4 gold. Maybe this applies to all hidden gold coins, I don't know. But at least it seems to be possible to manipulate it. Maybe you can spawn other items or ammounts of gold this way?
To replicate, reset the game, walk to the left, jump and use L+R to fall through the floor. This will spawn the gold coin. Loop through the floor again and you will grab it.
Edit: Also your updated run so far looks very solid and tight. Very nice. Keep it up!