I must agree absolutely with Robert.  The mailing address of the situs, which is typically shown as being on the street upon which the primary entrance of the home fronts, is a convenience, but does not establish location. 

Indeed, the term "legal description" is applied because it is the sole and absolute identifier of the land.

The borrower read and signed the document before a notary public.  The lender (not the borrower) received the signed instrument and sent it to the title company to be recorded.  The escrow officer received the completed papers, sent it to her title plant who reviewed it and sent it to the Recorders Office which approved it based on statutory criteria.

Since addresses and parcel numbers change frequently, they do not define property.  The legal description and underlying maps are the place to look.  In fact, one of the very first and most important principles of research is that you search by maps.

A component to this which is important to note, is that the Assessors Parcel Maps, Assessment Rolls, the Grantor-Grantee Indices of Official Records and Tax Assessment Statements do not, even in confluence, establish title.  The Official Records, meaning the documents themselves establish matters of title and claims, and the legal descriptions thereupon are relied upon by the tax payers, homeowners, and Citizens uniformly.

It sounds like your researcher did his job correctly and properly, and if the homeowner executed his documents incorrectly, then he should take that up with his original lender and title firm to see what instructions he issued and whether they were properly followed.