No, the problem is the "onAfterInitialise" trigger, which provides the joomla languge set by the session. Because it is fired before the "onAfterRoute" event. But you must route to know which language got selected.
VM used for vmText just the old code of joomla, which gets the language object for any call by the JFactory. We want to use different JLanguage objects in the vmText, so we cannot use anylonger the JFactory::getLanguage. We set now the language, which is also more performant. But when it is not set,... it throws an error. It was not a big deal to avoid this errors. But when the language is set by session to en and it is changed by the route to de,... the language en got already loaded and cached in vm. So we get the wrong language. Therefore the config has now a new parameter, "do not initialise the language".
We gain a lot advantages due this change. Only 3rd party using one of these both triggers notice a difference, the rest works as before.