Guys, I believe you all are missing the point here. MC would not learn the language any time soon (either by him trying or by someone using magic on him) because that is what makes this manga 'different' from others isekai mangas (the fact that neither he, nor we the readers can understand what is really happening around him, and just guess about it). Once he learns the language, the 'appeal' of it will be lost unless mangaka do something really interesting with it, which I doubt it.