I have sent some files to Graphisoft and have asked my coworker who discovered the problem to find out what font(s) were used in the original DWG as well as get the DWG author to resend the file with a known font (Arial). I'll let you know.
Regards,
Geoff Briggs
I & I Design, Seattle, USA
AC7-28, M1 Mac, OS 15.x
Graphisoft Insider's Panel, Beta Tester