There are multiple ways.

Each entry has a "Maintainer" link, if the maintainer of the record made his email visible you can mail him or her directly to ask for an update.

Alternativly you can send us a mail (wikimatrix@cosmocode.de) and we will either change it right away or forward it to the maintainer

You can also post a comment in the Wiki engine's forum which is usually monitored by the maintainers.

Finally you can add additional info for each feature in the according WikiPage linked to the feature table cell through the little i icon.