So you’re problem is you want to put asynchronous events in a time series. Using approaches like this, you can really only guarantee that an event happened after a point in time. I believe this is more of a use case for a blockchain than a DHT. But that kind of goes back to something I’ve mentioned before, I think there needs to be a blockchain zome. If you want to take events, and put them in a “block” of time, that’s going to be a straightforward way to do it in a decentralized system.
The issue with a centralized authority is that you kind of remove the benefits of a decentralized system. What you have is a distributed database with a centralized API. If I can only post once a signature authority approves my post, there’s not much benefit to using a decentralized framework.
I think IOTA came up with an interesting solution that could work in Holochain. If you say that the confidence of an events occurrence in time increases with the amount of entries downstream from it, it helps to create a chronology. It wouldn’t be precise but it would help to establish that events happened after other events. Once again, this is moving in the direction of a “entry chain”. So I make a post, other people make posts and reference my header hash. Other people reference those posts. I now have a growing dag of entries that can establish a chronology. If users post entries to this DAG, they will help to establish a chronology that will be reasonably secure.
I would recommend reading about Lamport Clocks: https://en.wikipedia.org/wiki/Lamport_timestamps to see how this problem was handled historically. Also, verifiable delay functions https://eprint.iacr.org/2018/601.pdf are a modern approach that have some really interesting applications to these sorts of problems. Solana uses a combination of these techniques to build a chronology, and I would love to see a translation of these concepts to a DHT.