4. Mixed-use properties. A property used for both residential and commercial purposes, such as
a building containing apartment units and retail space, is a dwelling if the property's primary use
is residential. An institution may use any reasonable standard to determine the primary use of
the property, such as by square footage or by the income generated. An institution may select
the standard to apply on a case-by-case basis.
If you have determined the structure qualifies as a dwelling either by square footage or income then you have a 2 unit dwelling IMO. If you have determined the structure is not a dwelling then you do not have a reportable loan.
The opinions expressed are mine and they are not to be taken as legal advice.