I googled this, looks like the biggest number in Construct is 9223372036854776000, which I think is less than 10^19, that's why last two events don't work.
So you need to invent some other way to work with such big numbers.
Maybe at some point in the game when the number of coins is already quite big (10^10 or so) and player doesn't care about hundreds and thousands, you can remove 6 last digits from the number and start counting in millions?