As @rsdenijs points out, internally Panel tries to define mappings from the underlying Bokeh properties to the parameter name in Panel in order to provide a consistent API. Internally this happens using the _rename attribute on the widget, e.g.:
Additionally, in order to support jslinking we also define so called _source_transforms:
which define transformations needed to map the property value of active back to the value you’d see in Python.
Any property that is mapped to None effectively can’t be easily linked because Python applies significant transformations to it that can’t easily be replicated in JS. That doesn’t necessarily mean it’s not possible but it’s a good indication that it isn’t straightforward.