I don't work for Wikipedia, but I do use it quite a bit and am familiar with its "Simple English" pages. As I see it, "simple English" isn't a type of English. In fact, references to "simple English" and "simple English" Wikipedia pages aren't necessarily the same thing. To me, the phrase "simple English" is synonymous with "plain English" and is tied to movements to make legalese as found in government and other such entities more clearly understandable to the average citizen.
Wikipedia's "simple English" pages are basically simplified, often truncated versions of the regular articles and likely attempt to refrain from words that would be considered past the 8th grade level — the level at which one should be able to at least start reading a newspaper. (At least here in the United States, budding journalists are advised to write for the "8th grade level.") But why speculate when Wikipedia defines it quite well:
For more, visit the page here.
My advice to you, if you want "simple Spanish," is to collect some word lists from kindergarten to the 8th grade and read books intended for those levels. Word lists may be easier to find in English. You can find some here:
Wordlists for Grades K - 8
Learn the Spanish equivalents of these words and you should be well on your way to a mastery of "simple Spanish." If you want to add reading to your learning plan, books in Spanish between the 4th and 8th grade level (ages 9-12) can be found here.
I don't know if Wikipedia plans to create "Simple Spanish" Wikipedia pages. It would be nice if it did. Wikipedia will appear to have translated your simple English page into Spanish,
but if you actually click on that link, it appears to be just a link to the main article in the other language — one without any attempts at simplification. Take a look:
But, short of that, you can take Wikipedia's simple English pages and have them translated by any number of machine translators. I recommend Reverso, DeepL, and Google Translate. You will run into a bit of trouble if you just try to copy and paste from the Simple English Wikipedia page (because everything on the page gets highlighted), but if you click on "Change":
You'll be able to highlight just the portion you want:
which you can then copy and paste into a machine translator. Then you will have the simple English version right next to the machine translated version and you've got your "Simple Spanish" Wikipedia page. It's kind of like a "reader" for Wikipedia pages:
The translation above is from DeepL. I could have chosen the other two I recommended, but in terms of readability and features, I felt DeepL does the best job of this. For example, with DeepL, if you don't like the translation or want to see how else a word may be translated, just click on the word (in the translated version) to see a drop down list of other possible choices. DeepL will change surrounding text as necessary to fit the new selection (if you choose one). This feature is immensely helpful when translating something that uses second person voice (e.g., tú vs. Ud.).
Ideally, one day you will be beyond the need or desire for a "simple Spanish." Few things, if any, are made better when they are altered for the lowest common denominator.
Note: This notion of a "simple Spanish" may also be something that some would confuse with "neutral Spanish." There is such a thing as "neutral Spanish," but this is more about stripping out regionalisms and using Spanish in a way that might be better understood by any Spanish speaker, regardless of which Spanish-speaking country one may be from. This is of special concern to filmmakers who want as wide of an audience as possible and wish to maximize profit at the box office. This excerpt I found explains it even better (minus my editorializing about motives):
Also known as “standard” or “international” Spanish, neutral Spanish is a convention that doesn’t technically exist as a language per se, but refers to the process of finding terms and phrases that are universally understood by all Spanish speakers or best suited to a multinational target audience.
You can find the full article here:
When (and When Not) to Localize into Neutral Spanish
The Wikipedia article on "Standard Spanish" also includes some information on "neutral Spanish." It also mentions motivating factors that include the movie industry (but I think you'll find them informative and worth reading), it also includes this:
Another motivator for the unification of Spanish is the translation by multinational companies of manuals, software, websites, etc., from English to Spanish. It is easier to use a neutral version of Spanish than to create different versions for each country or region. If it were done by country, there would be over twenty versions, and if by region it would be difficult to define which countries belonged to which region, as well as being complicated from the logistical point of view. The result has been to identify a neutral Spanish, a version that tries to avoid regional phenomena, such as the Spanish-speaking American voseo, or terms that may be identified with specific countries (for example, for “computer”, the term in Spanish-speaking America is computadora, except in a few areas that prefer computador, while in Spain the most frequent term is ordenador; as a result, Microsoft Windows uses the region-neutral term equipo, meaning "equipment"). This neutral language is developed with the help of glossaries that prescribe the preferred terms and the terms to avoid. It is a common occurrence in the computing field, because it lowers production costs.
The article contains a lot more information that I think you'll find interesting, so I recommend it, too.