The current machine translation systems work with parallel texts, and they will for the foreseeable future. However, to properly translate you need to understan

The current machine translation systems work with parallel texts, and they will for the foreseeable future. However, to properly translate you need to understand the meaning of a text, not just look up words or phrases in a table as is currently done (and using statistics does not address this). In other words, you need to have a connection between language and world, which is something only an intelligent agent has, hence the problem is AI complete. In terms of the nuances that were cited, it's not so much that they are infinite which is the problem, as other potentially infinite combinatorial systems such as syntax can be analysed effectively by computers. Rather it is the fact that choosing the right nuance depends on a completely arbitrary amount of context, such as the whole history of Russia when you're translating a Russian novel. So the problem is not impossible, but considering that even humans need years and years of study to do a good job at translation, I'd say machine translation that replaces humans is quite infeasible.