It probably doesn't have to be filed with the county because the federal court is in that county.  A thorough search of the records should include the federal courts when the federal court is in the same county. I don't see how any action in a federal court could provide the required notice to potential 3rd parties if they don't file something in the county records when the federal court is not in that county.  Which is probably why the title standards require the federal courts to be searched when it is located in the county where the property is situated.  (I would like to know how many people actually do that).

Best,
Robert A. Franco
SOURCE OF TITLE