Conversion of documents with foreign characters

Going down so many versions can create some difficulties. However as long as your colleagues are really on FM8 and not FM7 or earlier, it should work. I just tested it with a sample file.

First, make sure that you save your FrameMaker documents as "MIF 2017" and not as "MIF 7.0".

MIF 7.0 does not support Unicode and your Cyrillic characters will be lost (question marks).

If you are using some batch conversion tool (Plugin, ExtendScript, FrameScript) to convert all files in a book to MIF, make sure it actually creates MIF 2017 files and not MIF 7.0 files. (You can open a MIF in any plain text editor and check the version in the first line).

Make sure, that the fonts used in your Cyrillic documents on FM 2017 are also available on the system of the FM8 users. Also, make sure, that the font used on their system is actually the same font version. Some fonts grew over the years, so the font on your system with name "X" might support Cyrillic while the font with the same name on the old system might not have Cyrillic characters.

Last but not least: It makes life more easy for everyone if participants in the workflow are on the same FrameMaker version. And as FM8 is really quite old, your colleagues might want to consider updating to FM 2017.

In the FM2017 document, are the Cyrillic characters Unicode, rendered in a Unicode font, or are they 8-bit codepoints rendered in a legacy codepage font?

FM8 supports Unicode, so if the document is Unicode, the "?" merely suggests that the receiving system doesn't have a Unicode font for the typeface in use. Are they by any chance running FM8 because they are on Unix (e.g. Solaris)?

Now if the receiving system is FM7 or earlier, that's a can of worms you really don't want to open.