But the people of Guatemala and Costa Rica might not like being told they’re speaking Mexican Spanish. So the dialect spoken in those countries is called Highland American Spanish.
As for the Spanish language in Spain there may be ethnic issues involved. There are people in Spain who do not speak Spanish - the Basque and the Catalonians for example. So they might object to hearing the language being spoken in Madrid being called Spanish, with the implication that it’s the national language. They might rather say that language is Castilian, which implies it’s just one of the languages of Spain.
Frankly, I watched some British movies where American subtitles would have come in handy. I am specifically thinking of Peter Capaldi in “In the Loop”. I remember several times thinking, “Are those real words or is he just making them up?”.
There is nothing Danny DeVito could do that could possibly make this film any worse. Why do a film of Dr. Seuss if you don’t trust the original material? Once again, Hollywood has proven that you can’t add storylines to Dr. Seuss without ruining it.