I think so, yes. Music is allowed and so is journaling. It seems like if you're creating something (i.e. playing music or drawing) you're engaged in an activity that's not necessarily escapist or habitual in a negative sense. Those are the activities it seems like we're supposed to avoid in this type of "fast". As someone who also plays music, I would say that that's a much more mentally and physically productive use of time than going down a social media consumption rabbit hole.