but it’s not helpful

Seems pretty helpful to me to direct software requests or bug reports to the place where software or bug reports are taken.

The Lemmy github page — like any github page — is indecipherable for anyone who’s neither geek nor nerd.

Huh? How’s it “indecipherable”? It has some code listed, then below that is a description of the project. If you just want to add a bug report or request a feature, you click on ‘Issues’, then you check to see if that feature request/bug report is already there yet, click ‘New issue’, select the kind that you want (“Bug Report”/“Feature request”/“? Question”). Then you fill it out in the template that they give you and click ‘Create’.

I’m neither geek nor nerd.

Okay, but I should hope you’re literate. It’s not “indecipherable for anyone who’s neither a geek nor nerd”; it’s actually extremely easy, and even if you don’t find it that way at first blush, you could just ask “Hey, I’m kind of having trouble with this; can anyone help?”

Is there a community about Lemmy software on Lemmy somewhere?

My dude, my guy, the reason it’s on GitHub is because that’s where the developers are.