I have found that the SequentialPlanner regularly becomes confused when it is asked to deal with relative time concepts like "last wednesday" or "5 days ago". It will often try and make use of the supplied date() skill, adding a parameter to offset it (which is not supported). I propose that we add two new skills - one to find the date of the last instance of a given day name, and another to provide the date x days in the past.

Pull request adding these will be sent soon.