My suggestion would be to add a 'world' argument for the following objectives;

• Break - "/q objective add add break {} {[hand]} -w (world)"
• Mobkill
• Kill
• Place
• Collect

It could also work for these objectives;

• Milk
• Fish
• Shear
• Tame
• Dye

Objectives are going to have conditions assignable to them, so this feature is already in roadmap.