When will I be able to play?

126 years. Which is to say; when it's ready. There is no defined schedule and this is a hobbyist project.

What can you say about legal issues?

Erupe is legally in the clear.

Legality of things is also an irrelevant matter when you have Capcom money to throw around.

Distributing anything else could cause issues as everything belongs to Capcom or parties such as Gainax, Kodansha, Shaft etc. as well as various artists and voice actors.

Why can't I have quest files or similar?

Helping with development does not actually need any of the files not on archive.org.

You had twelve years to play the game. Increasing the chance of exposure to Capcom and the risk someone monetising the content or server is not a good trade off for 'playing on a partially functional server earlier'.

Why is there not a public server?

Public exposure on a larger scale is undesirable, especially with a new Monster Hunter releasing soon with very substantial reasons to believe it's getting a PC port.

There are ultimately no real benefits to random people playtesting, things which are broken are mostly simply not implemented and known about.

The server is also not developed enough to support large amounts of players, and has myriad features partially or hackily implemented or which are simply absent completely.

When security and general stability is up to a higher standard things might open up for those in the Discord, but there is - as always - no fixed timescale.

How can I help?

The core server is on GitHub, you can fork it and look at things there.

If you want to help with translations, you can read the guidelines here. If you aren't in the Discord and can justify wanting access you'll get an invite in a reply (assuming there is not simply a public invite live at the time).

Packet Captures are completely non-public, but will eventually be sanitised and put out for things that still need work done on them.

It's also important to keep in mind the ongoing work in all aspects is very ad hoc in nature, there is not a centralised team or plan.

Where can I find the old website's content?

You will always be able to find the original Frontier content at mh.fist.moe.