It would appear that when tasks are first created, they are sorted among the various Hearthlings, and that the only way to reassign them is to cancel the command and then reissue it. If there was a task list, and each 'ling completed the task nearest them and then picked up the nest closest one to them from the list, it would solve issues with buildings not completing, mines not completing, and anything else that requires one activity to be completed before another. I think the 'lings probably bog down trying to complete their long lists of activities, and I’ve noticed a lot of problems with buildings and mines not finishing if I reassign the job of someone in the middle of a building. Completing the job closest to them when they complete the previous job would improve their general efficiency. (Currently it appears they try to finish the task closest to the camp banner from their own personal queue).
Crazy loving this game so far, keep up the great work!