11 months ago someone already found out that Mendix does not fully support JSON in import/export mappings and asked about this on the forum. Now it's part of the documentation that certain characters are CURRENTLY not supported, suggesting. I ran into this while trying to implement a SCIM provider where property names such as "urn:ietf:params:scim:schemas:extension:examplename:2.0:User" are normal and even required in some cases.
I would like Mendix to strengthen it's JSON support by allowing all characters to be part of the property name.