Your proposition is that we should add a new category 10-13?
It does increase the average temperature of the Mild climates.
It could look like that?
sheet31.png
Gave it the color yellow and named the other category below as Chilly. That looks good?
Are there any other changes I should make for the temperature?
You think we are good with 6 precipitation categories?
It would be easier to add new temperatures or changing them than adding new precipitation categories. So if the precipitations look right with 6 categories, we could add one temperature category.
I think the most problematic Db/Dc area is in Siberia and your changes did not improve anything in that region.
Also, I don't know what map you use as reference, hopefully the one Kottek because the one at Wikipedia seems pretty flawed. For instance, it shows a Dfb climate around the Bay James between Ontario and Quebec but that is clearly a Dfc area.