I would look to this statement in the regs
Based on Reg C 1003.4(a)(9)-3:
3. Multifamily dwellings. A single multifamily dwelling may have more than one postal address. For example, three apartment buildings, each with a different street address, comprise a single multifamily dwelling that secures a covered loan.
There is also the definition of Dwelling in 1003.2(f)-2
2. Multifamily residential structures and communities. A dwelling also includes a multifamily residential structure or community such as an apartment, condominium, cooperative building or housing complex, or a manufactured home community. A loan related to a manufactured home community is secured by a dwelling for purposes of § 1003.2(f) even if it is not secured by any individual manufactured homes, but only by the land that constitutes the manufactured home community including sites for manufactured homes. However, a loan related to a multifamily residential structure or community that is not a manufactured home community is not secured by a dwelling for purposes of § 1003.2(f) if it is not secured by any individual dwelling units and is, for example, instead secured only by property that only includes common areas, or is secured only by an assignment of rents or dues.
If your townhomes are all part of a housing complex, then together they are a multifamily dwelling.
The BOL thread titled HMDA Multifamily Property or Not, posted 10/19/18 by DixieLee provides some great discussion on this topic,
Expect the worst, hope for the best and you'll never be disappointed.