Would be good to create a timestamp to each record to record data freshness. As for example systemcostindex is only cached hourly, to the hour is sufficient.
Along lines of:
var timestamp = ("" + Utilities.formatDate(new Date(), "GMT", "yyyy-MM-dd:hh:")+ "00Z");
Secondly, would also be good to have dump to CSV option on each update, will allow history to be captured for analytics. Naming could be "yyyy-mm-dd hh00 systemcostindex.csv" etc.