Last year, I sold my house.
As I couldn't be in Peru to sign the paperwork at la Notaria, an agency inmobiliaria did it on my behalf.
Before getting the poder from the notaria, I needed to go migraciones to get a ''permisso para firmer contratos''.
I strongly advice that before going ahead with the transaction that you get a copy of el titulo at los registeros publicos and get them to block it to avoid that someone let's say 5 minutes after you get the titulo sells the property as well.
The poder must also be registered at SUNARP.
You must also asked the person who sells you the property on behalf of the seller to see a copy of the passport of the seller and ''permisso para firmar contratos''.
As in your case, the seller is Chinese, he must have had a visa issued by the Peruvian consulate in China in order to travel to Peru. Check if the dates of the visa, entry and exit stamps of Digemin and the date on the permisso para firmar contratos are correct.
Also check that all the arbitrios, water and electricity bills are paid and that there's no MORTGAGE on the property.
If in doubt, pull out and look for another house. Don't take any risks. There are enough properties for sale.