Hi,
You could create a custom resource files MyCustomResources.resx should be the English version and MyCustomResources.sv.resx for the Swedish version, put them in the App_GlobalResources folder and specify the resourceFile setting when configuring your custom profile field. For the resourceFile name you would use MyCustomResources without any extension. Then use a labelResourceKey with English chars to avoid the error. Use the same English keys in your resource file and then enter the Swedish translation in the Swedish version of the file.
http://www.mojoportal.com/userprofileconfiguration.aspx
Hope it helps,
Joe