Neatline timeline date display customization and localization

Trying to localize the Neatline Time plugin for Polish language, I found that the month names and the item date displayed in a bubble cannot be localized.

I'd like to display moths names in Polish and dates in the item bubble like
in stead of
'Thu, 26 Nov 2015 22:10:00 GMT'.

I have 'pl' subdirectory in the 'views/shared/javascripts/simile/timeline-api/scripts/l10n' location with the proper locale files.
I also tried to force the plugin to use internal JS and added forceLocale=pl parameter to the timeline-api.js script initialization line but this made the script stop to work (no timeline was displayed).

There is also another problem.
One of my items has the string '1932-01-23' in the Date field. Ont the timeline bubble it is displayed as:
'Fri, 22 Jan 1932 23:00:00 GMT'

This looks strange for me because in fact the date should be 23'rd of January.

Can anybody help to solve this?