Hello! I'm having kind of the same issue also. Here's what I did to "solve" it.
First of all, I wanted to have a menu only in the landing page so people have to go back using "back" button to only one section page. Just as an app. I also put the Language switcher in my mobile header.
I've created the spanish menu and assign it to the landing page for spanish and it worked as I wanted until I had an english menu...
Then I can only have one landing page with one menu, not both. Also I cannot have an english menu assigned to some pages and the spanish menu to others... that's super strange but it is like that so...
I assigned BOTH menus to ALL pages, then specified languages to the different menu items (spanish for spanish items, etc)
And ok, now I have menus in every page... but multilingual. Also, this way you can have submenu items showed up for each menu. Hope this help
Cheers!