Hi Bernard,
Thanks for your update and sharing the details.
We could see that you have already applied locale using setCulture. So you do not need to use the previous update(include the locale property for the datepicker through edit Params). You just need to include the timeZonesNames.json into the files as in the below code snippet to resolve the issue.
Please get back to us, if you need further assistance.
Regards,
Pavithra S.