i cant remember exactly how it works, but door frames pull a texture from an adjacent floor tile or wall tile, cant remember for sure. try playing with the placement of your tiles,
as far as sloped roof corner, i have no idea. i havent really used the engine much since slope modifiers were introduced. try asking on the efpse discord https://discord.gg/dMd8e6bA you are more likely to get a response there.