The potential problem is that, as you have stated, GroupWise always uses the formats specified on the Format tab of the Date Time Options dialog. However, Formativ uses the date format specified by the operating system. As these may be different (which is why GroupWise has the ‘set GroupWise to system’ button), it is possible for Formativ to misinterpret dates on GroupWise items.
This means that my applet opens the calendar on the wrong date if GW and the OS are set up to use different date formats. It’s not a major issue, just a warning.