Great question and welcome to the BOL forums!
I would not consider multiple 2-4 unit buildings on contiguous parcels/lots to be a multi-family community. As far as guidance, one example that explains this approach comes from the 2017 proposal where they had talked about counting multiple dwellings in more than one location, but the 2017 final rule nixed that and clarified that dwellings in more than one location don't count as multifamily.
Specifically, the preamble to the 2017 final rule says this: After careful consideration of all the comments received, the Bureau now believes that it is not appropriate to add language to comment 2(f)-2 providing that a loan secured by five or more separate dwellings in more than one location is a loan secured by a multifamily dwelling. To ensure clarity and facilitate compliance, the Bureau is now changing the language proposed in the April 2017 HMDA Proposal to provide explicitly that such a loan is not secured by a multifamily dwelling. The Bureau is also altering the example provided to clarify that the multi-location loan described in the example should not be reported as secured by a multifamily dwelling.
In addition, the 2015 final rule does talk about multiple structures being on the same parcel:
In addition, defining what constitutes multiple properties may present challenges for some multifamily complexes, which may sit on one parcel but have multiple addresses.
Adam Witmer, CRCM
All statements are my opinion, not those of my employer, and should not be taken as legal advice.www.compliancecohort.com