In absence of any guidelines I'd argue that it is preferable to translate the metaphorical meaning, not the literal one. Especially in the case where the former exists, a literal translation is most probably unneeded.

I doubt though that the "己所不欲，勿施于人" is the proper translation here. HanDeDict gives the common German saying "Was du nicht willst, das man dir tu', das füg' auch keinem anderen zu." as translation which I would agree with (see http://tatoeba.org/deu/sentences/show/264541). This doesn't go together with the (indirect) English and German translations of this sentence. I don't however have any alternative at hand.

in fact is that case both can be added as separated sentences, now we will soon have tags, we will be able to tag one "litteral translation" and an other "proverbs" , this way people will know the "litteral" translation are not be translated again

It would be easier to translate if we add in some context.

"Why are you late every time?"
"Those who live in glass houses should not throw stones."

「你怎麼每次都遲到？」
「你自己還不是一樣？」

Well, if we are clear that the given metaphorical translation doesn't match and we fail to find a good equivalent, then I'd say we leave it open (and tag the remaining literal part like sysko described above).

This sentence contains an annotation with a variant translation. Please remove it and put it in another sentence, if appropriate.