Hi @Oliver01,
To confirm @KristenS_WF's assertion, custom data is not captured as part of Workfront's native Create Baseline functionality (which is one of the reasons we created our Baseline+ solution, which can capture custom data).
That said, since you are taking Baselines -- and assuming that your "Due Date" custom parameter represents what the In House planned completion date was at the time the default baseline was taken -- I suggest you add a calculated parameter (e.g. "Current Planned Completion vs Default Baseline") on a custom form attached to the In House task using this formula:
IF({defaultBaselineTask}.{plannedCompletionDate} < {plannedCompletionDate},"Late","On Time")
Speaking of which...as @CynthiaBoon recently mentioned, this Baseline Drift thread might be of interest to you, and at the next Strategic Admin Chat on September 18th I'll be offering of my favorite recommendations regarding capturing and tracking baselines.
Regards,
Doug