An alternative would be the option to specify an array of abbreviated names for weekdays and months. I have submitted a request for this, since I need it because some abbreviated names in dutch aren't really abbreviations i.e. the month march (maart in dutch) must be abbreviated as 'mrt' not 'maa'. However as this would also solve your issue, perhaps I can enlist your support for my request? see: http://highcharts.uservoice.com/forums/55896-general/suggestions/2296431-abbreviated-months-and-weekdays?ref=title
An alternative would be the option to specify an array of abbreviated names for weekdays and months. I have submitted a request for this, since I need it because some abbreviated names in dutch aren't really abbreviations i.e. the month march (maart in dutch) must be abbreviated as 'mrt' not 'maa'. However as this would also solve your issue, perhaps I can enlist your support for my request? see: http://highcharts.uservoice.com/forums/55896-general/suggestions/2296431-abbreviated-months-and-weekdays?ref=title