The date picker is showing the months and days in English only, regardless of the language the user chooses.
- Go to your profile > Manage Account.
- Click on Account Preferences.
- Choose a language different from English.
- Open an issue in Jira that has a Date Picker field.
- Select a date.
The date should be displayed in the language that the user chose.
The dates are only displayed in English. See the image below:
Currently, there is no known workaround for this behavior. A workaround will be added here when available