About model and data exchange with 3rd party solutions: Revit, Solibri, dRofus, Bluebeam, structural analysis solutions, and IFC, BCF and DXF/DWG-based exchange, etc.
This is a bit tedious to solve, but not impossible!
You must ADD some code to GDL script:
1. OPEN your Zone stamp object....Select the Zone and use Ctrl+Shift+O (PC)
2. In PARAMETERS window check that there is a variable named "ROOM_AREA" (see picture Room Area - Cost_01)
3. Pick the button located right of Master and write the yellow marked text
4. 3. Pick the button located right of Parameter and write the yellow marked text (see picture Room Area - Cost_03).
5. Close the main GDL window and SAVE when asked to do it.