It seems to me that a full mastery of language requires a grasp of semantics, that is the ability to understand what a sentence means. I doubt it's possible to do that without having basic common sense along with an overall representation of the world, and that looks very close to strong AI, imho. So I'm not surprised computers keep on struggling with language applications. Once they succeed strong AI will not be muc…
I think the 'overall representation of the world' requirement is pretty key here. Language in AI is often treated as its own class of problem, with the assumption that there is somehow enough signal in the raw mess of examples provided to any given learning system (usually just plain text, stripped of any prosody, emotion, cultural context, imagery; any of the other modalities of communication available to a demonstr…
Another grounding source is related to ontologies. We are already building huge maps of facts about the world like "object1 relation object2".
Another source of "common sense" is word embeddings. In fact it is possible to embed all kinds of things, like, shopping bags, music preferences, networks topologies - as long as we can observe objects in context.
Then there is unsupervised learning from video and images. For example, starting from pictures, cut them in a 3x3 grid, shuffle the tiles and then task the network to recover the original layout. This automatically extract semantic information from images unsupervised. A variant is to take slides from video, shuffle them around, then task the network to recover the original temporal order. Using this process we can cheaply learn about the world and provide this knowledge as "common sense" for NLP tasks.
I am not worried about grounding language. We will get there soon enough, but we're just impatient. Life evolved over billions of years, AI is just emerging now. Imagine how much computing power is in the collected brains of humanity, and how much computer time we give AI to learn. AI is starved of raw computing power and experience yet. Human brains would have done much worse with the same amount of computing.