Reported by jteh on 2012-07-20 05:05
In Adobe Reader, if a node doesn't explicitly specify its language, it is inherited from the nearest ancestor that does. However, if such a node is re-rendered due to an event, the inherited language will be lost. This is because the node is rendered into a temporary buffer, so it isn't linked to its ancestors yet.

Unfortunately, the problem is more visible than just forms, etc. because Reader fires a valueChange event on the top node of a page when it scrolls. Thus, whenever you switch to a new page, the inherited language is lost for the top node of that page.