Diversity is quite a broad topic, and while I have lots to say, let’s start small.
In my experience, one of the least controversial way to get a diverse user/contributor base would be IMHO translation.
The project summary speak of Iranian developers, but I do not see any iranian living in Iran listed as such on Preparing the User Research . So maybe there is something to do there first, and long term, having a plan to get the software/website/documentation translated in Farsi (and others languages, obviously) would be a way to keep contact with people living in Iran and see if the project is solving their problems.
That’s my non controversial idea. The slightly more controversial idea would to drop the mandatory 2FA requirement for the forum.
While I think that’s a good thing for something sensitive (provided sensible implementation), I think that’s totally overkill for a forum where you expect less comitted people.
People who own a u2f key would be surely ok, but the experience would be worst for others if they just have a smartphone and blocking if they don’t. So forcing 2FA mean the people with u2f key would be more at ease to participate than those who don’t, and so select the community based on that criteria, which seems like a problem.
I would be more controversial and say that reducing friction by offering more than login/password option can be helpful to attract more than the usual crowd of free software die hard. But adding more options requires to drop the 2FA requirements, if I am not wrong (maybe that’s on gitlab).
Now, I get there is also a spam filtering issue solved by 2FA auth, and not much options on Discourse. I also dislike moderation as much as anyone else.