I have been encountering similar problems with japanese text under wine+ubuntu. I resolved most of my character mapping issues by replacing the fonts in ~/.wine/drive_c/windows/fonts with those found in C:\Windows\Fonts on a separate xp install. I do still occasionally come across a few characters that don't get mapped properly and display as a colon as you have described above. I don't think this is a problem with foobar itself but with wine's international support which is rather dismal IMO (Have you been able to input anything using SCIM with wine?).
Foobar is not designed to work on wine. Don't expect to find much support on these forums for your setup but I would suggest continuing to plug away at different fonts until you can find something you can live with.
When selecting a font there is a pull-down menu for "Script". You may wish to try different scripts for your font. If you are using exotic characters you may need to choose a script other than "Western". You may need to explore using
WineLoc to reveal additional script types.