Sorry for the delay of response.
I am very busy with my principal work.
I have tested RealCADD with Catalina (installed on an external SSD) and I think that there is a problem with some files.
I have to test more.
I worked (a little) on v5, first to modify the system of preferences and I think that this part is finished.
Instead of DWG-DXF Converter, you can use this : https://www.opendesign.com/guestfiles/o ... _converter
And thanks for the DXF converter link – that looks like it will do the job OK. I have to do a lot of converting from early versions of DXF to more modern versions as my naval architecture program (MacSurf) is very old and exports to a DXF version that RealCADD can't open!