I'm using Optitex Marker 12 and I can't read any of these files because it needs to be closed loop. Can't you do it for me somehow?
not familiar with optitex all signtorch dxf files have all continuous closed polylines (unless filename ends with ~) in corel cad or autocad with all curves selected - they are all polylines and are all closed (see pic)
all I know about .gbr is it's used in PCB production and PCB software my standard vector/CAD software won't export .gbr afik I just don't have time to try but something like KiCAD (free) might do it - it imports DXF and exports .gbr