@nebulon Cool, it's a brilliant piece of the puzzle already, so the date columns are just icing on a cherry cake
To be clear, I dragged and dropped an already unzipped folder that resulted in what you see above. Your download a folder as a .zip and upload a .zip and unpack already seems to work very well!
If you want to put candles on the cake too: a left-column to tick multiple things, or some other multi-select method would be handy!