We don't use code.orgmode.org for Org's development.
But please clone Org's repo, make a patch - perhaps with https://magit.vc - and attach it to an email you send to emacs-orgmode@gnu.org: that's all it takes.
Then we will help with polishing your contribution :)
Alright. Now, let's say everyone is busy, and the maintainers have no time to review the patch. Who's going to remember that someone sent an email with some improvements a few months later? AFAIK There's no easy way to find all the emails with patches that weren't merged/(not) accepted/upvoted/downvoted/closed/etc. It's not easy to refer to the specific email; it's difficult to pinpoint the exact conversation around a specific change using git-blame. GitHub/Gitlab/etc. make all that a lot simpler.
Reviewers possibly use org-mode to keep track of those things. Would be trivial if Emacs is their mail reader.
For those who are really taking advantage of org-agenda et al, I'd argue GitHub issue tracking UI is far more restrictive for tracking patches.
If I were in that position I'd be duplicating issues into org-mode anyway (or using an Emacs mode to interact with/sync them). Maybe that's the missing link?
But please clone Org's repo, make a patch - perhaps with https://magit.vc - and attach it to an email you send to emacs-orgmode@gnu.org: that's all it takes.
Then we will help with polishing your contribution :)