If only using the brim texture it uses the profession head but if using the helmet/hat texture that goes over the head, the entire face becomes overridden by the base texture thus making it impossible to have a hat with a custom face for the profession... better explained by the pictures

just brim works, brim with hat doesnt

ive also included the textures i have in use

ps. the one in the background that looks like its working was when my base villager texture was also a snowman