The raised exception is "This character is not supported by this class of string". I think the solution would be to open the mse file stream as utf-8 encoded. I wonder if the importer would still work then.
No idea Did you try?
I changed the MooseModel>>exportMSEToFile such that it writes an utf-8 stream. Tested exporting and importing CodeFoo and works without problems so I commited the change to MooseDevelopment.
Mircea.