I’ve checked the code, and it appears I changed it some time ago. Probably at some one else’s request.
So now, if you have more than one extra menu item, then the main menu wil use the title hard coded into module.php (“Menu”).
If you only have one item, then the main menu uses the title of that item.
I thought about changing it so for multiple menu items (sub-menus_ the main title became the title of the first (lowest position number) in the list.
But I’m sure someone will want to use something completely different to that.
So I will need to modify the configuration so there is an option to over-ride the main menu item if you want, or let it default to “menu” or let it use the same as the first listed item. But that will take a little longer. It will be done before the next release though.