> I am not too familiar with antitrust precedent, but to what extent does the judge rule on how specific the data sharing need to be (what types of data, for what time span, how anonymized, etc. etc.) or appoint a special master? Why is that up to the judge versus the FTC or whoever to propose?

The judge doesn't propose, he rules on what the parties propose, and that can be an iterative process in complex cases. E.g.. in this case, he has set some parameters in this ruling, and set a date by which the parties need to meet on the details within those parameters.