Just tried it. Yes, on 8.1 INT I have ???? too
But on 9.0 RUS all is OK. ( I have no 8.1 RUS installed, but I think it will work too ).
Unfortunately, I have no good solution. But I think an easy solution may exists. May be it is required to change default archicad Font Script Code but I dont know Mac platform well. May be for this purpose editing resources is required.
I can offer little bit hard solution. It seems works, if autocad fonts were in the correct encoding.
Though layer names will not be actually cyrillic as the INT version does not use a cyrillic font for dialogues so it will look funny. Plan texst will be cyrillic if you choose cyrillic fonts.
You will need to enter 66 lines in the dwg translation dialogue : Miscellaneous / Character conversion:
ArchiCAD AutoCAD
Character Character
128 192
129 193
..... up to
159 223
Then
224 224
225 225
...... up to
255 255
And two more
221 168
222 184
May be anybody knows the right , easy solution.