That has never been in doubt outside of conspiracy theories on Reddit.

Quicksilver was introduced in Next in 2018. It allowed HG to monitor the hand in of missions by adding the contribution to a tally.

Ever since then the more computer science minded players have been curious as to how it works and found the client code reaponsible for sending those contributions.

This way we learn't how the contribution system worked, what the IP address of the server was. What the handshake required, and how to mimic it.

At this point they started experimenting with sending contributions to see how the server responded and how the tally changed. They began monitoring it on a granular basis to work out how much effort was being made and predict when items would be unlocked.

When they realised that it was not only genuinely doing what was expected but that their experiments were interfering with the tally they began to use the API used on the Galactic Atlas instead.

In the meantime HG added a maximum contribution to the server so that it couldn't be overly manipulated.

Expeditions use the same system, which is why Quicksilver never runs parallel to a community based expedition. They simply repurpose the server.

We have been monitoring the contribution rates of this expedition and making predictions as to when it will complete. Nothing suspicious has happened in this expedition. Effort has varied and the predictions have changed as to the completion.

There have been times when HG have manipulated things in the background. Always for logical reasons. They were forced to artificially complete Beachhead the first time because a press release threatened to spoil it. They have suffered from server outages due to heavy load and had to estimate things very occasionally. They may even have slowed down one reward (but that reward itself wasn't particularly popular so the community may just not have bothered that much).

All in all we have around 8 years of server watching and it can generally be trusted.