We apologize for the instability of composr.app and appreciate your patience. We are working on the statistics addon and trying to find an optimal way to store and render data. Unfortunately, we have yet to find a solution that can handle the traffic (and therefore, tens of millions of statistical records) of composr.app. We're working hard on one.
#1908 - Support importing of spreadsheets other than CSV
The 'Spout' library supports ods for a while now. I've reworked the excel_support addon as the enhanced_spreadsheets addon, as part of wider work on #3032. It's a lot cleaner and more flexible now.
I have already removed 'CSV' from the icon labels, but the screens themselves then go into detail.