Patcor

It is letting you know that the NVC has processed your application & has forwarded the physical files to your fiancé's embassy. If you don't already have it, you can request the case number & proceed to complete the rest of the required steps while the files are in transit (i.e., DS-160, paying your MRV fee, scheduling an appointment, scheduling & completing your medical exam, etc.).

It means your case has been transferred from the NVC at USA to the USA embassy/consulate in Lima, Peru.  You need to check your e-mail often, since this is the main form of communication the embassy will use to send you the next steps.  I would suggest you go here on VJ into the Peru portal to ask for further assistance AND look at the guide for K1s.

I googled it out and I found that I can addemn the case by calling USCIS and inform them about the application error and resubmitting the case. Do you think is a good idea? Or should my fiance just wait for his interview and mention this to consulate?

He is unfortunately. I gave him all.the information about my fiance kids and still didn't include them and I was going through the paperwork he sent USCIS and the part that says if he had any kids the attorney marked as NO. I do not what to think anymore. 7 and 17 year old. Yeah they are coming with my fiance that was the plan since the beginning.

you can try to call USCIS but getting thru to anyone who can actually help u is about impossible 
U need Tier 2 person
 
u have to take full responsibility for the  I 129 that u signed

I sent printed pictures for my rfe and got approved. Make sure write the date and people names on the back of the pictures and also occasions.