Example Google Apps Script functions to normalize non-ASCII characters and insert a timestamp, when a new row is created.
Basically I sloppily added various Vietnamese accented characters to this Gist example: https://gist.github.com/akora/51b2933a2554776d7144#gistcomment-2936646
Blogpost about Apps Script in general, onEdit and timestamps here: http://blog.danwin.com/how-to-automatically-timestamp-a-new-row-in-google-sheets-using-apps-script/