Currently Plotly has poor i18n support.

• You can not change d3 locale (issue How to make localization for type date in axis ? #380)
• Adjustment of rendered precision on date axis does not work when applying custom axis.tickformat if dates need to be rendered differently because of locale. If you want to keep that feature you have to patch hardcoded format strings:

  plotly.js/src/plots/cartesian/axes.js

  Line 879 in ad88139

  var yearFormat = d3.time.format('%Y'),

• Error messages, notifier messages, hover texts for default mode bar buttons are hardcoded in english Localizing modeBarButtons? #288

Currently I have to manually patch plotly for each release, which is pretty annoying.