As the best practice for APIs is to always return time back in UTC read more here Law #4: Return it in UTC an option on these two elements would be nice so that we can format the display in some other timezone (e.g. format based on the timezone of the logged in user).
As far as I can see the date(time) list elements use fecha.
From what I see fecha doesn't support this, instead something like moment-timezone should probably be used for this.