I agree that Artha would be a valuable addition, however, I would rather get a small team together, transfer the repository to GitHub and work for a new release.

Why was it rejected this time?

read just above your question: closed this task as a duplicate of T1867: Artha.

What's the proper way to get a package reconsidered? Since the reason for the last rejection is no longer policy.

Unless there are new arguments, it won't be reconsidered.
Reason for the rejection was given here

It's my understanding from listening to Ikey that the policy has changed. That a package is no longer rejected simply for being unchanged for a few years. If it is shown to still be packaged in at least two other mainstream distributions.

So the policy hasn't changed?

I am not aware of any change.
The package inclusion policy is here

So it’s allowed but at the descretion of the package maintainers. Thanks for taking the time to answer my questions.

I’ll try to compile it myself.

It looks like you'll need this.

https://wordnet.princeton.edu/wordnet/download/

Personally, I think the best would be to wait that the 3rd party repositories are replaced with the new flatpak-based system.
The problem with "dead-on-arrival" (DOA) applications like this one, is the dependencies... they might stop working with newer version of dependencies which would prevent upgrade of other applications which require newer version of the same dependencies. So I understand that Solus team doesn't want to handle this and eventually offer a bad experience to some users (either by not upgrading some software or by adding some in the repositories and removing them some time later because they don't work anymore).
In such case, it's better to refuse them immediately - which is the case of this app.

If my understanding is correct, flatpak could solve this problem as it allows to package an application with its own version of the librarires and run them in a kind of sandbox, so 2 or more applications could run using different versions of the libraries.