X2 is not old or outdated by any means. To me it is actually amazing. Why the rush for a new version?
Every system needs updating, let alone a complete and feature-rich Forum system, I don't think going from 2.2 to 2.3 needs to take years, but I know that Xenforo has a lot of improvements between subversions.
I create small to large products and almost all of them need small updates, code improvements, modernization, updating technologies, adding features, in short it is part of any system.
In case Xenforo has an excellent product, they just need to focus more on communication, maybe increase the team and have a clearer release plan, maybe big new feature releases every 6-12 months and bug releases every 1-3 months or as soon as possible.
A detail is also the Technology, really, we have PHP 8.2 since 08/12/2022
https://www.php.net/releases/index.php and as far as I know Xenforo doesn't have a 100% compatible version with it.
As far as I know Xenforo is based on the Symfony Framework
https://symfony.com/releases and I don't think it's updated based on version 6 or even 5 which is LTS (I could be wrong I didn't analyze the code).
The JS used are also being updated, in short, all technology is being updated, now the Xenforo team does not seem to be standing still, but without closer communication it is difficult for us to know how the maturity of the project is in the technical matter and even of the company, until today I don't want to know how many developers work on Xenforo, so I see only 1 that is more present at least.
In short, Xenforo needs to be treated as a company that is what it is and also perhaps with a footprint more focused on Open Source with more transparency, this wins over customers and builds loyalty.
They can also post more articles, to show that they are active, each new version could make a post, teach how to create modules, finally participate more openly, but I understand that it is just ideas and that if the team is small it can be difficult.