Trying to figure out if it’s possible to retrieve the information about date/datetime/time formatting patterns and the default timezone for Confluence cloud instance
The REST API you referenced returns the default locale of the tenant. For example, it might return "defaultLocale":"en_GB". Once you have this, it depends on your tech stack, but you’ll probably be able to format a date/time in accordance with the locale. In addition, some tech stacks might allow you to convert a locale into a date/time pattern. Confluence Cloud users have a time zone property, but I’m not aware of the tenant having a default time zone property.