I'm sure you're already familiar with the following, but could be interesting for others.
Spain (the country) has multiple official languages, one of them being the European Spanish called Castellano Spanish. This is what people refer to as "Spanish language". However there are others, like Catalonian, Galician, Basque, Valenciano etc. languages, which are also "Spanish", but not mutually intelligible with Castellano. These are completely different languages on their own, and interestingly, in the case of Basque, not even in the same family of languages.
Even sticking to Castilian, the regional accents and vocabulary choices could differ. You could pick a neutral Castilian accent from Spain, potentially alienating Latin Americans but I think this is often received OK if a little off. You could pick something that sounds like Mexico or Colombia, which are each common choices for things with an international audience. But then, say, an Argentine accent, to pick out one, would sound pretty different.
