Neither buyer nor seller are anonymous. Your bank knows your ID-verified identity and that you have deposited X talers. However, nobody knows when, where, or even if you spend those talers. You are free to spend talers on eg. a e-book about Tiananmen Square and the bank/state will never know that you did. The seller, on the other hand, has no protections, and will be destroyed for selling an e-book about Tiananmen Square. Also, you can't realistically buy a physical book about Tiananmen Square because you will give up your address to the shipper and by extension to the state.
If my understanding is correct... it's not good enough. In a free society we should be able to both purchase and publish e-books about Tiananmen Square, and this does not permit that.
What? You can definitely publish about it in a free society, and cash anonymity has nothing to do with it.
That's pretty hard unless Taler is very widespread. I could see a world in which that would work - if people generally made all small purchases in Taler and it replaced cash. But there's no reason for governments to buy into that (except as maybe an intermediate pretense after ending legal cash payments entirely), and no reason for large corporate chains to buy into it unless (and maybe even if) government has bought into it (too much legal exposure for too little benefit.)
So any merchant who dealt in Taler would be maximally scrutinized, and whatever exception they were riding in order to be allowed to deal in Taler would be too valuable to give up through selling forbidden books. Like maybe your doctor could deal in Taler fairly freely, and he's not risking his medical license to screw around in politics.