Spreadsheet functions do not include a consideration for different timezones. In programming jargon, they simply deal with naive Dates & Times. This is by design, and makes working with the Date & Time formulae a good deal easier.
The IndustraForm spreadsheet engine assigns a timezone to a form instance when it is first created based on the Regions Master Data configuration (see j5 Framework Help for details). This uses the Operational Area associated with the form.
Before using IndustraForms in a multi-timezone j5 system, the Regions configuration must be completed.