No, that doesn't work. Maybe with the 505, but definitely not with the 350.
If you miss one ore two fonts, reader will crash.
If you copy all three fonts in the folder, the reader will get confused as described.
If you copy additionally the link to a disitinct font, DICTIONARY will not work as mentioned earlier.
Solution in the end was to dump down with Borodas software part of the firmware of the reader, open it with WinImage, extract the file named SWNMTeb.ttc which I could not find over the internet and copy it additionally into the font folder.