Well, most people probably think: this will not happen ... it happened to me today. Over 300 terms in Itzgründisch together with their German translation ... all of a sudden I got:
Wir bitten um Verzeihung.
Ein Serverfehler ist aufgetreten. Warten Sie einen Moment und versuchen Sie es dann erneut.
Weitere Informationen finden Sie in der Hilfe zu Google Text & Tabellen.
That is: they are sorry, there is a server error and please wait a moment and then retry. You will find further info under Goolge Text & Tables ...
Well that moment now has been some hours ago. The funny thing is, just a few moments before I thought: well let me download the file. Like so often I feel things before they happen, but if I had not done that ... what then?
So this is to tell you: keep copies of your google documents somewhere ... data loss is always just around the corner.