Just to be sure (because it's going so slowwww): are there any more ways to obtain / buy carnival tickets, other than playing the 4 games in the Carnival (bluff, pond, toss, balloon)?

I don't think so, but pond is your best bet. I don't think I've won anything from the bottle toss...ever. Bluff is the second best if you are good at it, and balloon can occasionally yield good results.

The fastest way to get them is to play the pond game every twelve minutes as much as you are able.

out of the thirty day cycle of the bathhouse, two of those days have a chance of giving you some. It's a small amount.

That's what I was afraid of. Thank you both for confirming!

You are welcome.