I defined some new content types using Dexterity in an add-on created using mr.bob. However, if I use this content types inside a Plone 4.3.6 site that use plone.app.multilingual 2.0.0, then they are not displayed in the portal-globalnav. This issue does not occur in a site that does not use the plone.app.multilingual add-on.
I found another odd behavior when using plone.app.multilingual. I created the content types A and B where A and B inherit of Container and Item, respectively. I created an instance a of A and an instance b of B where a is in the root folder of the site and b is inside a. Without plone.app.multilingual the breadcrumbs said "You are in Home / a / b" when I'm in b. However, if I do the same using plone.app.multilingual the breadcrumbs omits a, i.e., said "You are in Home / b".
Plone has a related feature called "navigation site root", which is available as a behavior for new content types. When a container has "navigation site root" behavior, it itself appear as site root, also resetting portal-globalnav to display its own direct children.
The later odd behavior described should happen, if content type A has navigation site root behavior enabled.
plone.app.multilingual creates language specific navigation site root folders into Plone portal root, and automatically redirects browsers from the real site root to the default language folder. Therefore plone.app.multilingual prevents folders directly under the plone portal root being displayed in portal globalnav, effectively allowing each language to have its own globalnav tabs. Yet, a container added direclty under the language folder should be displayed in globalnav.