CCP would have to pay to use such an API commercially, and there is no gain for them to do so. They are not going to attract or retain new players by implementing translation in chat - most players are already bilingual or, being that the player base tends to be highly educated and computer literate, able to use translation software via alt-tabbing and are not terribly inconvenienced by doing so. It suffices to say if they’re playing EVE Online in Tranquility and stuck around as long as they have, they don’t need this.
Self-segregation by language isn’t necessarily a bad thing, it’s the reality of the world we live in, and the nuances of language translation are going to wreck havoc in numerous situations, especially in fleet coordination, even moreso where slang and EVE-specific jargon that isn’t readily translatable is involved. CCP could and to a large extent should invest more in localization efforts and giving more love to non-English languages to bring them to first-class status (Spanish doesn’t have its own forums section!?), but there are issues with this as well (see related thread recently posted)