Translation of convertible in Spanish

This is actually a big mistake as a community always should grow by a few percent. The reason is quite clear: The young people will need to support their parents once these are unable to work.
I told them that in Europe not everything was perfect. I told them that there were also very dark times in that continent and that even in peaceful times live was not always easy as they had thought.
About multiple translations: We want students to memorize 'idioma' and 'lengua' as they are both very common. The best we could do is to place them in 2 different lessons, so that users learn them both.