It's just the same meme you have always seen, saying the same thing it always says. If you haven't seen the meme before, you won't know what it says. Everyone is just having fun "translating" what they have already memorized (meme-orized?).
Sync supports native OCR extraction and translation of images as well as fully translating posts and comments. I don't even recall it having that feature in Reddit, but it's pretty awesome to have now.
This is the first time I see a non-English meme outside of non-English communities. And you can easily block the latter. And I wouldn't really count this as non-English, since the main text is English and the meme text is a known meme already.
Nobody is pretending. People either already know the original meme and use it to deduce the translation, or they have the minimal understanding of Spanish required to read the text.
I'm assuming by "original meme" you're referring to a meme with a completely different image that you wouldn't know what it is unless you read Spanish.