This sentence doesn't make sense. You are not supposed to add sentences in languages you don't know.

Actually I try to learn Japanese, though of course I'm still at the beginner's level. Could you please explain what is wrong with the translation, I found it on the Internet and it was a Japanese site. To my, again, beginner's view it looked correct but sure I won't pretend to be an expert and will not argue with a native speaker in the least. Could you also provide your own version please.

As for the part that we're not supposed to add sentences in languages that we don't know. I've seen translations by others on Tatoeba into languages they don't know very well. Sooner or later their mistakes simply get corrected by others. I don't see a problem here really.

Anyway I would be grateful if you could help me with this specific sentence.

You're not supposed to pick up sentence in another websites unless you have the right to.
だから、気をつけて！

I'd translate the sentence like this:
私の世界で、誰もはポニーで、虹を食べて、蝶のうんこをしてる。

Thanks a lot. I usually check and correct everything I use. I guess my Japanese is just too bad. I won't experiment with unknown Japanese sentences any more. Thanks! And may I post your translation too or could you perhaps do it yourself?

I prefer mookee ( or someone else ) check my sentence before ^^" I'm not either that good at japanese.

Everyone makes mistakes and beginners have right to learn here. However, we should not try to add a sentence with a structure which is still way beyond our grasp, I think.

The translation you found is really bad. If I had to, I would translate it into English like this:
In my world every pony, every one of them, is a betterfly of poop which eats rainbows.

Based on the Quazel's sentence, I suggest this:
私の世界では誰もがポニーで、虹を食べて蝶のうんこをしている。

Thanks a lot. I hope you don't mind if I replace the wrong sentence with your version.