When we use non-ASCII characters in smb.conf, we cannot change 'unix charset' parameter via SWAT because SWAT does not convert the encoding of non-ASCII characters, which depends on 'unix charset' in smb.conf. I think it's good that this issue is a limitation for Samba 3.0.0 and will be fixed later.
unix charset can be changed in (post)3.0.7 swat however there is no conversion of smb.conf being done. I don't think this is feasible anyway, there would be also conversion of filenames be needed in case unix cahrset is changed.
originally reported against one of the 3.0.0rc[1-4] releases. Cleaning up non-production versions.
sorry for the same, cleaning up the database to prevent unecessary reopens of bugs.