To understand a subject at any meaningful level, you have to be willing to go deeper than understanding the surface details. You can get the gist of a topic by skimming a book about it, but you’ll only become a master by exploring it deeper.
That’s not to say you can’t learn other things, or even that you should specialize in one area. In fact, please don’t specialize in one area. You will become a single-faceted person with little else to identify with. You should, however, be making more sacrifices. Say no to more things. Not so you can have other experiences, but so you can focus on the tasks you’ve already agreed to dedicate yourself to.
You could rapidly accelerate your language learning, but since you aren’t focused, you make slow progress. It’s not vital that you learn a new language, so that’s all right. But what about the things you really need to improve on? You need depth in some areas and as of yet, have been unwilling to make the sacrifices to get there.