A building that has multiple uses is not a single family private residential property. This is a mixed use building, being there is a business in one part and a housing unit in another, so it doesn’t go against PRP rules.
Even if the building switches to housing only, it’s not a single family home, as each floor could hold 1 housing unit, so a minimum of 3, 1 on each floor. Single family homes only have housing for 1 family, not multiple. Duplexes are homes that have 2 housing units in the same building, for example, and they are not considered single family PRP.
Being this isn’t single family PRP, I would follow what has been outlined in the criteria clarification for buildings such as this:
We also have houses in the US that used to be single family PRP but have been fully converted into something else, such as a store, cafe, or museum. I know of a cafe where I live that’s in an old house, and it’s been a business of some sort for over 25 years.
You need to see the building for what is currently is being used for, not what is could be used for or what it was in the past.