It's odd to only get a mail address - policy at libera dot chat - and no further formal contact information of the non-profit as a legal entity in Sweden.
I suppose you could try an inquiry via the Swedish tax office asking them for a formal statement from the public record. I don't know any Swedish but I suppose there might be a search engine which lists public information about non-profits?
Even so, there are other hints: the footer features a link to a Github organization where you can easily track development in the open. Of course, that still doesn't give the project a clear, identifiable "face" or formal point of contact.
Other commenters argue "anonymity is how Freenode got big, and how the Internet used to work and that's perfectly fine since it fosters trust."
I think this only holds so much water today. It's not about a relationship between users of a service which provides the affordances to hide behind an anonymous handle. This is about the relationship between users and the operators of a service. You trust that an operator "won't do harm" when you log onto their service.
Such trust is tenuous at best if the decade has demonstrated. Legal frameworks such as the GDPR and privacy laws exist for the exact purpose of protecting users, and creating a legal liability on the part of all too zealous operators of services.
Moreover, the GDPR framework actively tries to de-incentivize gathering and storing any personal data which can be tracked to identifiable individuals without due cause.
Testing Libera Chat's trustworthiness would be, theoretically, as easy as sending a formal subject access request under the GDPR rules to the listed mail address.
Now, I'm aware that all of this are round about ways of figuring out whether this service is legit. It would help if their website just listed formal contact and legal details that identify the legal entity which can be held liable.
Then there's Freenode Ltd which is a UK company. Since Brexit, the GDPR doesn't apply. Given the latest publicly published updates, I don't feel similarly confident about the credibility of any statements regarding the safeguarding of personal data, nor backed by a similarly strong legal framework as far as my own rights go (I'm not acquainted with British privacy laws).