Writing in Spanish is, in many ways, much harder than English. For one, words and sentences are longer, so length becomes an issue. An ample vocabulary, when used generously, comes off as corny and melodramatic. And production concerns, such as performances and permits, require different approaches.
Sounds nit-picky, but it's actually quite important. I'm currently involved with several projects, all of which shoulder distinct issues. At the end of the day, putting a good movie out there is the objective, but it all starts out with the script, and it's in this area that I feel many Spanish-spoken films fail.
Forget structure, or story, or cultural elements, or even style, for crying out loud. If the script reads poorly, the film will as well. The projects I'm involved with, hopefully, will not suffer a similar criticism. I am trying my best to make sure that's the case. But doing so in Spanish... it's the same tools on the same kind of engine. It's just a hardware store under a different banner.