There are a few things to be aware of…
The book used 4 people to a family, where acks assumes 5. Use the “able bodied” numbers for families, and ignore their population counts. The levels are completely different, and you’ll have to wing that.
The “support” for all of the Towns and villages is done through a completely different set of assumptions than acks. They assume each town hex has farmland and a high density of farmers around it, but no extended domain. I don’t have the population numbers they used at hand, but you will run into problems running that btb acks, because almost the entire wilderlands will be “wilderness” and the villages and Towns wont support an acks style domain around each village under “wilderness” pop densities. I think making each marked village hex “civilized” with one days walk around it “borderlands” made things work out ok, but I’d have to look.
I didn’t see a clear distinction between castles and Towns, from the acks perspective… Both were civilizaton centers