Bobby Cuellar is of Mexican descent and speaks Spanish. I agree that Latino coaches are underrepresented when compared to Latino players but the Twins aren't completely ignoring it.
Cueller was born and raised in Texas and went to the U of Texas about as american as you can get. This is just my opinion but speaking spanish doesn't mean you can relate to players from Latin America and help mentor them. Of course it doesn't mean he doesn't help either.
However, I think that an ex latin player that could relate to coming to a new country, new language and having suceeded at making that transition would be helpful.
A question I'll ask is do the Twins have anyone in the dugout during the games that speaks fluent spanish?