Listings in the directory are based entirely on the content of the website. For a site to be listed in the Spanish-language part of the directory, it must be in Spanish (although it can obviously be in other languages as well, for instance English and/or French), and possible to use for somebody who does not understand any other language than Spanish.
So if your site is entirely in English, then it is unfortunately not going to be listed outside the English-language part of the directory. If it has regional relevance for Central America, you can suggest it for review in the relevant country and locality under Regional/Central_America (which is where English-language sites about that part of the world are collected).