The Sort by Location button's script is quite something. You should look forward to that! But first, we'll start with the Sort by Time button.
Edit the script of the Sort by Time button, on the first card.
Type in this short handler:
on mouseUp global gReminderData set the itemdelimiter to tab sort gReminderData numeric by item 4 of each showdata writedata end mouseUp
Get mentally prepared and then edit the script of the Sort by Location button.
Type in all of this:
on mouseUp global gReminderData mobileStartTrackingSensor "location", true put mobileSensorReading("location", false) into tLocation mobileStopTrackingSensor "location" set the itemdelimiter to comma put item...