Basically the any element i.e. the part that sais <any namespace=".....
means that from there on any element can be present.
This means that there is no way for Mendix to determine what it can expect and thus there is no way to (decently) map its input to mendix.
That is why the any element is not supported. If you want to add support for this xsd you will have to determine what kind of responses you expect and change the xsd accordingly. Without having some example messages there is no way that we can determine that for you up front.