Second, the building code, IRC/IBC, defines a townhouse as zero lot line (zero setback) homes that are on their own separate parcels and share a common wall.

It's possible what you have done on your own isn't even to code or done correctly so you could be losing value if you haven't been careful.It's great that you took action.

Do you need to go through a special  use or variance request?

I have been using the BIS site, and as Llewelyn mentioned, the Dept of Finance tax code is 2 family, but no CofO from DOB to support. 

I was talking to a cost segregation specialization vendor that does this nationwide.

However, a CPA specializing in real estate can offer insights that may help you avoid common pitfalls and optimize deductions early on.

In the last few month we had 2 visits of officers from the Special Enforcement office, the first time I spoke with them they said they were just trying to see the airbnb listing to make sure it was in compliance with their requirements, I had guests in the room and I didn't let them in.

Specifically one that specializes in investor-focused lending.

Known for its "Blue Light Specials," the discount chain was once a retail powerhouse with over 2,000 stores across the U.S.

Consider building relationships with local brokers who specialize in multi-family units and may have off-market opportunities.