I think one of biggest reason it blocked was because of emerald. If possible, I'd like to suggest change it into easily craftable, but bit effort needed ones. Such as smooth stone block. And adjusting some high level trades, I think it would be usable without effecting much on server economy.

 

Emeralds are very rare, having regular trades would not only flood the market with emeralds but spiral their prices into the void. Like you mention, changing the trade item would be fine except choosing such an item would effectively kill its own economy, and then any trades offered would then would crash any value held in the items tradable as they would become infinite.