All that I really know about SACIE is that I have a pull-chain derailleur branded 'SACIE Trionfo'. Everything else is slightly spurious information gleaned from moderately inconclusive Google searches and the guesses of Italians that I have talked to.
It's possible that SACIE is the 'Società Anonima Commerciale Industriale Emiliana', a company based in Bologna, Italy. This company appears to have been established in 1936 and to have still been active in 1948.
SACIE also appears to have manufactured (or possibly wholesaled) a range of cycle and motorcycle components and possibly complete motorcycles. In the late 1940s there was a lively market in Italy for small petrol engines that could be fitted to pedal cycles, for pedal cycles prefitted with these engines and for very low-powered pure motorcycles that used a lot of bicycle parts. The companies servicing this market were not clearly in either the bicycle industry or the motorcycle industry - but were effectively part of both. I believe that SACIE was one of these companies.
SACIE may have, at some point, been bought by Ducati, the now-famous manufacturer of high performance motorcycles. Ducati is also based in Bologna. It may be relevant that Ducati first entered the motorcycle industry, in 1946, by producing the not-at-all-high-performance Ducati Cucciolo 48cc engine - which was designed to be fitted to a standard bicycle. The Ducati Cucciolo went on to become the market leading small engine for motorised bicycles.
Finally, it may be worth noting that moped manufacturers in France and Germany have been known to fit derailleurs to their mopeds. It is not impossible that the 'SACIE Trionfo' derailleur was created to be used on a motorised bicycle, rather than on a purely pedal driven model.