Usually it's because the number of albums and songs released in that language are not enough to supply demand. Like say an artist releases an album in French. Not all the songs are going to catch on.
It's that way with most any album that is released. So that limits it even further. 10 songs on the album, but only 2 or 5 are going to get interest.
Then factor in not as many albums are released in French. If albums are limited, then the top 40 is going to have to get supply somewhere else. If you become used to other languages being in your countries top 40 it becomes normal, and you just get used to not understanding them.
You appreciate them for the melody and chord progressions rather than it's message through words. Tons of albums are released in the English language, so in the USA there is plenty of supply for the top 40, and no need to draw from other resources. Foreign artists will often release albums in English as well, hoping to chart on English language charts.
The US top 40 is extremely difficult to get into.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.