Thanks for any suggestions. First and foremost, ask God. He knows the plans He has for you and for your children. More on that in a moment. Bathe your choice in prayer, and anticipate the Shepherd's sure guidance.
Any language study is beneficial.
Perhaps a beginning in Mandarin Chinese that you drop, will turn out to be a springboard to a successful attack on another language. Don't be too quick to label attempts as failures. Learning to speak a language is more like practicing basketball than studying history. Another comparison that can be made is that of learning to drive a car. One can become quite a good driver without ever coming to an understanding of how the car actually works.