Lumberjack currently has three stat improvements instead of useful upgrades. So some ideas that could replace them include:
[*]Ability to build log holder (stationary structure that you can put logs into similar to putting into a cart/boat/wagon but holds MUCH more and tells you the stats of the log (quality and wood type) when you hover over it).
[*]Ability to burn down logs into ash.
[*]Ability to carve sculptures which provide a small buff to some stat when within a small radius around it. (So for instance you make a carving of a duck that gives +5 cooking that sits by your fireplace.)
[*]Ability to redecorate/recolor a structure without affecting it's quality.
Honestly, most of these don't even need to be tied to the Lumberjack credo and would be fine on their own. But damn is it depressing looking at some of the credos and not seeing any good reason to spend the effort on them unless you are bored.