Hi Eduardo,
Thanks for contacting Syncfusion support.
The Timezone API of Datepicker is used to control the conversion of Date values to its equivalent UTC date to avoid differences in Timezone across different cultures. Since this conversion is done at server, you need to define the Timezone API in the wrapper itself to store the Date values as UTC Date in the server.
Whereas, setting the Timezone in Javascript will only let you convert the received UTC converted date from server to the client Time zone to be displayed in the browser.
In short, setting Timezone in wrapper will convert the posted date from client to UTC, to be saved in server and setting Timezone in Javascript will convert the Date value received from server to equivalent client Timezone to be displayed in the browser.
Regards,
Deepa L.