Conquered cities and towns

[QuintusSertorius]

The game can't display negative properties for those building capabilities; whenever it says "+-" it actually means "-".

There are no negative effects of having "foreign" buildings in a settlement, that's an RTW mechanic that wasn't adopted in M2TW. If they're providing a benefit, leave them be. The exception is other faction's colony buildings, which not only give you no units, but may prevent you building colonies of your own.