I need help for non-maintainer upload of package mah-jong.
I think what you may be looking for is package salvaging... [1]
mah-jong is a board game, already packaged in debian release.
However, the last time of its package dates back to 2012. While there are some
new upstream version and bug report, it seems no reply from the author.
I wonder how to contribute to this package when I could not reach the
original uploader.
...based on the lack of contact with the maintainer. If you follow the steps in the link, you could add that package to the Games Team and then add yourself as an uploader if you want to keep working on it.
I also recommend joining the Games Team, if you haven't already.
-Olek