Marriage license translation (difficult question)

My wife is about to submit her N-400. Our marriage certificate is from her country and in her language, so we need to submit a translation along with the copy of the original document, along with the translator's certification of competency. I have two questions about this:

1) Can my wife translate her own documents and provide certification? I have seen some people on various forums saying that they did this, and neither the N-400 instructions, nor the "General Tips on Assembling Applications for Mailing" on the USCIS site, nor the "Information about translating Foreign Documents" on the State Department site say that you can't translate your own documents. But several reputable immigration websites say things like "please note that the petitioner or the beneficiary cannot translate the documents." Can anyone clarify this?

2) Is an old photocopy of a translation and translator's certification from a foreign country acceptable? We still have copies of the translation that we submitted when applying for her green card four years ago. The translator's certification doesn't follow the form that USCIS suggests (I [typed name], certify that I am fluent etc. etc….), and doesn't include any address, but otherwise says basically the same thing. Can they make a problem out of this?

There is only one adult person that we know of in our city who speaks my wife's language, and he is wary of getting involved in someone else's immigration/citizenship business, so he won't translate and certify for us. The only translation agency that does her (rare) language is in Washington D.C. at her consulate, which might take weeks (we know about their bureaucratic inefficiency from experience). So any information, experiences or advice anyone can share would be deeply appreciated. I'm especially interested in any experiences of problems that people have had with old or inexactly certified translations, or with translating their own documents.

Thank you.

I translated my documents for green card, and later for naturalization, myself and had no problems with that. If you are anxious about doing it, probably you wife knows somebody (relative, friend..) in her native country, who knows english and could sign up translation and send it to you?
I do not remember them asking for translator's address, by the way - just to certify that they know both languages and that translation is full and correct.
In any case, unless you are american and your wife applies after 3 years, not 5, based on marriage, the marriage certificate is not a very important document. But if it is the case, then I would be more careful.