openutils-mgnlmessages is a custom magnolia module which adds a GUI for translating messages inside the magnolia admin interface.
This is how the translation page looks:
This module currently requires magnolia 4.0.x
The module needs to be installed as usual, by declaring an additional dependency into your pom or by manually dropping the jar into magnolia.
You also need to configure in magnolia.properties:
info.magnolia.cms.i18n.MessagesManager=net.sourceforge.openutils.mgnlmessages.i18n.OpenutilsMgnlMessagesManager