Since 2019 I have been trying to sort out the lens question and think that 'lock down' has provided enough time for thought, and tinkering, to solve this.
Illustrations from Italy often show a modern lens fitted such as Schneider or Nikon lenses but the fitting looked strange. In the event it became clear that the lens was fitted into a slim extension ring that probably lived with the lens. When removed this left a 39mm threaded plate similar to almost all modern enlargers. The lens therefore required a short extension or lowering to engage the Auto Focus with accuracy. A trial and error search of all suitable 39 mm rings (standard Leica thread) then took place and in the end a 8 mm ring was found. This is very thin but is probably the second ring in the FED range of extension tubes that are easy to find, designed for the obsolete range of Russian/ USSR/ Ukraine FED and Zorki cameras. Having the correct thread at each end it instantly paired up with a Nikon 50mm f2.8 (First Type) and 'lo and behold' I had automatic focus.
A special note- a 7 mm ring also exists which does not work, at least with the machine I have. There is another small point to check. Sharp focus may only be achieved on three sides of the empty film frame which is simply adjusted. The enlarger has a unique negative holder with a separate mask that can be used to display negative margin numbers. This mask can be rotated in its holder to conceal such numbers - as I prefer to work. The mask is not locked horizontally and can be slightly adjusted by hand for those who are after margin printing effects. By and large, it's just an annoyance that is easily removed and in any case it would be hard to get the full 25mm x 37mm 'Leica' edge in prints.This small problem results from the edges in the carrier being at very slightly levels unless adjusted and the effect has no bearing on negative focus.
There are two important cautions here. Firstly, The figure of 8 mm is the measured depth of the ring taken from each bearing face, ignoring thread depth. With the ability to reproduce the odd Leica thread pattern it would be quite possible to introduce a small degree of fine tuning to a custom adapter with set screws but, for me, the solution as stated seems to work!
The second caution is rather more simple. The Auregon is provided with a basic means of manual focus. To allow the Auto focus cam to work fully the sliding bellows adjustment should be moved to it's lowest point against the final stop at the base of the vertical slider that supports the bellows and locked out of the way.
Examination of the cam wheel suggests that only one shape was produced and made to work for all (nominally) 50 mm lenses, possibly by shims,or custom adapters.
Hope the above helps any reader with a similar problem!