Thanks. Unfortunately, the images are all missing.
And LibreOffice would display the images in the RTF document in a different size (a tiny block).
If my old Mac display would work, I could have been able to send the document over to CUPS via Netatalk, and make a PDF out of it. Unfortunately Mini vMac can't connect to that VM on the LAN...
Anyhow, it is scandalous that opening legacy documents became such a PITA.