Downloading bulk data via FTP can provide you CSV files, organized by dashboard, Node ID, data channel, and month.
This is a trick that will convert timestamps to readable date and times.
Apply the following formula to convert the unix timestamps: =(((F2/60)/60)/24)+DATE(1970,1,1)
Note: F2 can be changed to the another cell
Format the cell, and select the desired date/time format.