Expected Behaviour
Seeing as how the Canyon biome and its variants can be seen as a variant of the desert and badlands biomes, both of which cause newborn villagers to take on their desert skin, villagers born in the Canyon biome or any of its variants would take on their desert skin.
Actual Behaviour
Villagers born in the Canyon biome or any of its variants take on their plains skin, which can be seen as unfitting of both vanilla behaviour and the climate.

This behavioural quirk likely affects other Terrestria biomes; I only noticed it in the Canyon because that is where our villager breeder is. If you wish to tackle this issue, here is the Minecraft wiki's information on which vanilla biomes house which villager types, for reference: https://minecraft.gamepedia.com/Villager#Appearance

Also, as a side effect of this, fisher villagers buy oak boats in the canyons biome, when they should buy jungle boats as desert villagers do. This would apply to any other Terrestria biomes with erroneous villager skins, as the boat trade is tied to the villager's skin.