Is there a way to track when the Helpers view their schedules or sign into When to Help?

You can tell if a Helper has viewed the latest version of a published schedule by going to your Schedules section using either "By Helper" or "Statistics" schedule views. That will show an eyeglass icon  to the right of their name if the Helper has viewed the latest version of that particular schedule week. You cannot tell the exact timestamp of when they viewed the schedule, but you can tell if it has been viewed since you last made changes to their schedule data.

Those views also allow you to see if the Helper was emailed their most current schedule  or clicked to confirm receipt of that schedule email.

You can see the last time each Helper signed into their account by going to your Helpers section and clicking the "Select Columns to View" link and checking the "last sign in" option then Update Display.

Also, you can see Helper information.