Bonjour,
the body of the machine seems to me to be welded and not drawn from a mold, which would lead me to think that it is a personal design and manufacture based on an invented or found plan and not a production of a known manufacturer.
Furthermore, personally, I have never seen this design of management of the reverse of Stephenson.
In France, we have had several famous steam designers who used to share their plans but never worked with a manufacturer.
Example 1;the DN15, welded machine, plans designed by Delaby & Neyrolles :
Example 2, the AL5, plans designed by André Lecomte, made from foundry parts that the modeler had to acquire from a colleague who had made a small series to share the costs :
Example 3; the BR2034, plans designed by Bernard Retif, here aluminum cylinders lined with bronze but could also be full bronze :
These gentlemen have never seen a manufacture machines use their plans, which makes their quality and rarity exceptional.