It costs money. Many folks may not think that's a big deal, but it is. You have to hire people who have some degree of credibility to do the job of moderating and be fluent in multiple languages, where there is a minimum of English and/or Japanese and the language in question. A year of Spanish in high school isn't gonna cut it, despite what some special folks may want to believe.
Before you can even hire someone, you need to go through the channels/departments to create the position (not hard given it already exists for other languages), find someone qualified to advertise said position in the other language (as well as possibly write it up in your own), then advertise the job, and all of this also costs money. You then have to go through the typical interview process to find someone who not only qualifies but would be a good addition to the team. You don't want some stuck up d-bag to start causing problems. All of this takes time and money. For as simple as hiring might be for a small private entity, it's typically a totally different beast with an internationally large one.
Then there's the need to figure out where the line is drawn. Just because there might be a small amount of players who speak a certain language, doesn't mean they must branch out and support it. There's a reason why in the case of the forums, we have separated communities based on language. Someone posting in a language other than English, on the English forums, will have their thread deleted/locked/moved, depending on what it is. The same happens if someone posted on the Japanese forums in a language other than Japanese. Likewise for the French and German forums. It's just a way to keep things structured and organized, typical protocol and nothing personal.
A language like Spanish, for as widespread as it may be, is hardly even a thing in Japan. Heck, most of them may never even see a native speaker of any foreign language outside of English in their entire lives. When you look at their target demographic, Spanish-exclusive speakers are not a significant concern of theirs lol. Unless the company and their subject service or product is being marketed to a specific group of people, they are not obligated cater to outside audiences.
It would be nice to see every form of division be catered to, but that's just not realistic lol.