[pyrale]

> actually decentralized transactions between two offline parties can take place.

The schema they use to explain the system's mechanisms clearly shows an exchange that needs to be audited:

> Payments are made after exchanging existing money into electronic money with the help of an Exchange service, that is, a payment service provider for Taler.

That is, the transaction can be offline, but it eventually needs to pass through a central point to be effective.