I'll need help with this one. I can't find core MW message for minor edit. The search results on our codebase are:

'editpagelayout-pageControls-minorEdit' => 'Minor edit',

'multiwikiedit_minoredit_caption' => 'Minor edit',

'wikieditor-publish-dialog-minor' => 'Minor edit',

/includes/apis/WOM_SetObjectModel.php:
'minor' => 'Minor edit',

/includes/api/ApiEditPage.php:
'minor' => 'Minor edit',