I-751 interview: real risks

What is the name of your state? CA

We've lost a large number of joint documents and are ready to file my I-751. I'm trying to get duplicates, but it's nearly impossible (thanks sprint, thanks SBC !!!) If I get called to an interview, and they consider that I don't have sufficient evidence, are there risks of fines and prison for my husband and me ? can they just decide it's a fraud even though it's not ? Or will I just be refused the green card, in which case my husband and i will just move back to friendly Europe ?

No risk of fine or prison, and surely you can come up with alternative documents evidencing the bona fide nature of your marriage. Current bank statements, utility bills, insurance, credit cards, car registration, mortgage/lease, etc., photos and affidavits of friends, neighbors.

Please let me know if you have any additional questions or if I may be of further assistance to you in this matter.