You could check your DWG with some other DWG-reading program (like Autocad) to determine where the blame lies. There are free DWG readers on MacOSX. (Do a search in this forum) But you could check it by opening ti in Archicad too!
I have a feeling this is a Powercadd issue. If the drawing unit and the scale is set similarly on both sides, I've never heard of a text sizing problem in DWG conversionbetween Autocad and Archicad.
AC4.1-AC26SWE; MacOS13.5.1; MP5,1+MBP16,1