You wouldn't really be able to contribute even if it was well documented without PHP wizardry
As for feature suggestions, I recommend using https://github.com/Heyuri/kokonotsuba/issues - don't look at how it says "issues", feature suggestions are welcomed too!

I'd liek to go through it and translate all the comments at some point (maybe we'll find some hidden secrets!), but I've got a lot of other things on my plate rite now

Regarding things I would add in a magical world where I can PHP (and have infinite time and resources):
- automated thread autosage status based on how far down the index it is, rather than how old the thread is (would also be undone if a thread goes back up the index due to deletion of spam/crapfloods). This means that thread lifetime will adapt to the speed of the board, emphasizing newer threads over old
- old threads knocked off the index in the last X hours/days are temporarily stored/archived somewhere so they can be restored in case of a big crapflooding attack
- report system with some form of notifications to mods when the number of reports hits a certain threshold
- alternatively, a Futaba-like "del" system that allows users to self-autonomously ban users per thread and delete posts using a threshold for how many "del" s are received
- other Futuba self-autonomy features like OPs having mod capabilities over their own threads, able to activate IDs or set their thread to autosage when making a thread, etc.
- going even further, an elaborate user moderation system like open2ch's where OPs can assign other posters in their thread as mods or hand thread ownership to someone else (useful for longer-term threads)
- more of open2ch's kewl features in general. The site is a wonderland of innovation!
- thumbnails for SWFs and built-in Ruffle player
- bring back the "switch post form position" feature so I can see what I'm replying too without using quick reply
- bring back the "current users" counter
- a fancy stats page where we can see PPDs and history graphs/data liek 4stats.io and a few Japanese sites have
- custom kaomoji buttons and some kind of custom emote feature (maybe it could be vote-based)
- better voting system than Polls@Heyuri in general (apparently kokonotsuba has a built-in polling system that's not enabled - is it good?). There's an old series of Japanese BBSes from the late 90s that was kinda like /vote/, but with the ability to comment and add your own answers. That would be my inspiration

Oh, and of course a fixed ban revoke feature, as well as the ability for mods to append a message to posts/replies without triggering a real ban or warning

I'm always afraid that my funb&s are gonna get taken the wrong way, and I know from experience that it's very annoying to have written a whole post only for it to get eaten by the warning page

...and the return of the Overboard, but would also be versatile enough that it can also display Strange World posts, Oekaki posts, etc.

>the ability for mods to append a message to posts/replies without triggering a real ban or warning
You can do that by changing the IP addresses at the "IP Addr:" field to something like "1"

>You can do that by changing the IP addresses at the "IP Addr:" field to something like "1"
...I knew that

*adds "improved ban instructions on ban page" to list*

Here are the labels on the repository, I made an "idea" label for your such ideas.

Who knows, maybe some leet developer will liek your idea and work on it

>>62282
mods can append messages and warnings on posts without being banned.
like that one post that had a "THIS USER HAS BEEN RED TEXT'D" or something, it wasnt a ban either... i would kno cuz it was me