Hi Marcin,
In my understanding, person other than the maintainer can also send patches.
In the `Contributing to Vim` [1], it is mandatory only to contact the maintainer.
I think the following procedure is appropriate:
1. Share the contents of the patch (file or URL) to haskell-cafe ML (maintainer).
2. Wait for several days (a week?)
3. It is considered good if there is no objection (no reaction).
4. Send pull-request to vim project on github.
(Also add URL of cafe mail to PR)
[1]:
https://github.com/vim/vim/blob/master/CONTRIBUTING.md#syntax-indent-and-other-runtime-filesRegards,
Takenobu