Once the tournaments get going, the auctions might heat up.

What do you other players think of a currency exchange, where players can bid Thaler to buy Gold or bid Gold to buy Thaler, similar to the raw material exchange?

I'm thinking that Gold gets removed from the game by being spent on various things, like Troop Master, Trade Master, production bonuses, etc. Allowing players to sell their Gold for Thaler would mean that some players wanting more Thaler would have an incentive to buy some Gold, and thus support the game financially.

Meanwhile, active players with more Thaler than they know what to do with would be able to trade them for something more useful to them.

It doesn't solve the Thaler problem though, since as long as the only way to use the Thaler is at auctions of player items, they just get recycled. The supply is going to continue to increase, until the merchant starts selling something to remove them. We would still need some kind of sink for the Thaler, to remove them to counter inflation.