Deciding points
Points are the most important decision you will make in Chantico.
In Chantico, you stop arguing about who is (or isn't) contributing. Instead, you debate what the points are worth.
Decide points together
Decide points together, as a team. Everyone that particpates in chores should be at the table.
Ensure everyone agrees on the point values. It is not enough that everyone participates; everyone must agree. Without agreement, there is no ownership or commitment.
If you cannot reach agreement, at least get to a place where everyone is willing to give it a try. Points aren't set in stone, and you'll probably tweak most of them.
Iterate on points
Keep tweaking the point values. You won't get them right the first time.
Points should be just high enough that everyone says "I'd do that".
If a chore is not getting done, bump the value. If a chore is getting spammed, lower the value.
The atomic chore
Determine your least loathed chore. This will be your smallest point value. Think about other low-point tasks as multiples of this atomic chore.
For example, your atomic chore might be "Take the garbage to the bins", worth 5 points. You can then ask "How many garbage-to-bins equals one unload-the-dishwasher?"
Reference chores
Establish a few reference chores that everyone agrees on. For example, everyone firmly agrees that unloading the dishwasher is worth 20 points, and vacuuming the house is worth 40.
Once you have reliable references, you can fit chores between them.
For example, "I'm not sure how many points dusting should be, but I know it's bigger than unloading the dishwasher, and smaller than vacuuming the house."
Accept some slop
You don't need to get the points perfect. If everyone is contributing, and everyone feels appreciated, mission accomplished.
Some people will want to create spreadsheets and find some cold empirical truth. If it keeps them engaged, that's fine too.