Thank you for the explanation.

I get it now. It is all thanks to separating the operation as 1. agreeing on WAL, 2. executing after waiting all WAL agreements stabilizing.

There is a separation between the two. This can introduce waits (which could be theoretically unbounded for EPaxos but Tempo and Accord bounds this).

Maybe in some sense this is in the same spirit of Calvin's serializing WAL first and executing it later. But Accord avoids a single entity doing the serialization and achieves it via a leaderless Paxos approach which uses dependency graphs for WAL serialization, and later using another protocol for WAL execution after settlement.