Here is why I have generally seen with them. This is contingent on which career track you take.
If you speak Spanish fluently, you will go where the agency needs you and it won’t necessarily be that great of a spot. Other languages may get you a good spot but not necessarily. Had a friend fluent in Japanese- he told me he was one of only a couple in the agency- he was in Boise but did go to Japan occasionally when needed.

I applied to the DEA in my younger days- can speak Spanish and Japanese. The agent who processed my original app was a member of the church and told me to re-do my application and take all references to speaking Spanish off if I ever wanted to be in a decent assignment. I got a job offer but opted to go the local LE route because I didn’t want to move every two or three years.