Due to the Modelica naming conventions, the URDF or SDF file that is translated should contain model name, link names and joint names with only alphanumeric or underscore characters.
This restriction can be relaxed if single quoted idents are utilized, e.g., a name like my joint would no longer be invalid if handled as 'my joint'.
From the Readme on Naming:
This restriction can be relaxed if single quoted idents are utilized, e.g., a name like
my jointwould no longer be invalid if handled as'my joint'.