I finally found the recent discussion of this set of plans on the Busker
Organ Forum. It was under the heading "John_Smith_20er_tracker_bar".

https://www.tapatalk.com/groups/buskerorgan/viewtopic.php?p=8275#p8275 

The French system is a good one in terms of performance, but more
complex than the "German" or "English" ones. In my opinion, a novice
building in isolation is far better off starting with simple John Smith
plans, then moving up on a second project.

Wallace Venable