Interesting. I'm trying it out but getting "You are not allowed to get a DomainDescriptions you did not create!" after creating a custom Data Selector.
Yes saw that in the logs and actually already wrote you an email. At the current point in time, we do not allow to change DomainDescriptions other people created. In this case, we save the one the user wanted to save and log it (that the work is not lost) and then incorporate the changes our self. This will change in the future. Sorry for the inconvenience.