Thanks for the rules explanation. This explains a lot.
I read a lot of board game rules, and to me, there still seems to be some confusion between "Green card in the deck" and "Green card draws". If I understand correctly, you have 3 Green Steel ledger/Green card draws at the start, and each subsequent turn you gain Green Steel ledger/Green card draws based on unused blue steel (plus unused green steel)?
You start with a pool of 4 green cards in the green card deck, and you can get more via parlor upgrades. I assume this doesn't get you more green steel ledger/ draws.
The carousel seems slightly wonky when you have more "Green Steel ledger" than green cards, but it seems it just shuffles the green discard? This also messes with the blue card that is based on cards in the discard.
As such the benefits to getting more green cards in the green card deck doesn't really increase your ability to build track, just changes the distribution of green card bonuses?