Gramps:Side bar translation
Manual on how to translate the sidebar, and how it works.
Only a system administrator can edit the sidebar labels, so you should contact e.g. bmcage and give him the translated strings.
How to edit side bar
Read Mediawiki Manual:Interface/Sidebar.
What to translate for Gramps
The Gramps sidebar is defined by MediaWiki:Sidebar.
The target links are fixed to the English pages and cannot be changed. The first column is the target. Click on it for those defined by Gramps. The last columns contain the labels that should be translated: