Excuse me, in "
but that will require our CSV files to have one column each, which -by now- is really convenient"
I tried to say that having the 4 series in a single file is really convenient. Changing it to single series per file would require to have 4 separate files.
About your idea, yes, it can be an option but... as our CSV files are about 5MB each, loading 20 MB per graph would be significatively slow for an Internet client.
We'll weight the options, and decide the best way to solve it.
Thanks for your replies !