Well looking at the code it is a trivial change so if you want to try it I would be happy to help get it going. The javascript portion was made completely flexible. The only thing holding you back is the list of short code arguments which are in easy-chart-builder.php in a method called 'process_shortcode'. Go to line 285 or so.
Locate this statement:
'group12values' => '',
Just copy and paste that line and continue the numeric count:
'group12values' => '',
'group13values' => '',
'group14values' => '',
'group15values' => '',
...
You will have to do the same for the markers (group12markers ...). they are just below these.
Then I think you are done! If your chart fits let me know and Ill see about making the change official.