Not really. Just like English, the standard variety in each country is considered equally "standard".
> I understand it to be based on Castilian.
I'm not sure what you mean by this. As far as I know Castilian is just a synonym for the Spanish language (as opposed to other languages of Spain e.g. Catalan). So the variety spoken in Guatemala and the one in Tenerife are equally "Castilian".
But, people always deviate from it, though in my experience in word meanings and pronunciation, never in grammar to a degree that it become intelligible to another Spanish speaker.
The toughest film to listen to for me was "The rose seller"[1] (1998), took me like 10m to get my ear accustomed to their pronunciation.
It being so artificial means that it doesn't fit anywhere, even it if's becoming more common (Kids are growing up listening to Media dubbed to it, so it's not weird seing a Child "speak like a cartoon" for a while until their local dialect kicks in)