Hello se77e,
All 3d software has a spatial limit which is around 80km for Archicad. It is then necessary to draw close to the absolute origin of the working file.
To have a DWG with the project-specific reference system, all you have to do is compile your DWG from archicad in a worksheet in which you have previously discarded the reference DWG (far from the origin). Once your DWG is repositioned, just re-publish your DWG from the worksheet.
Christophe - FRANCEArchicad Designer and Teacher
Archicad 15 to 27 FRA FULL
OS 11.6 Big Sur - MacBook Pro 2017 - 16Go RAM
"Quality is never an accident ; it's always the result of an intelligent effort" John Ruskin