Hey! I'm glad you like the game! I apologize for the late response.
There are a handful of families that do not have their house size marked, and they are assigned a specific house size. This is intentional, the original thought being that you couldn't trust every person to fill out an application form correctly, and these families could be assigned to clowns with adaptable house size needs (with the added fun of being able to take a risk and bet on an unknown, hoping it works out).
The code guarantees an appropriate family is pulled from the database, for every clown each day (excluding "zoo bound" clowns). So if the only compatible family is one that has no house size listed, than their house size must be the correct size for the clown. It's just an extra layer of puzzle to make some days a bit harder.