Your query caught my attention while I was searching my Chini ancestry. My mother's maternal grandfather David Chini b. about 1875 came to the U.S. from Segno (exactly where I'm not sure) through Ellis Island on 31 July, 1893. He settled and lived in and around Flushing, Ohio.
I noticed in my searches for other related Chinis coming through Ellis Island that there were a few Magnanis travelling with other Chini's as well. I wasn't sure if you were trying to find info on your grandfather Carlo Magnani here in the U.S. or if you were only concerned with his info in Segno. However, I have seen the manifest where Carlo Magnani came through. He came through on 26 November, 1905 and he was going to his brother Angelo Magnani in Bridgeport, Oh. Your grandmother Luigia came to the U.S. through Ellis Island on 23 March, 1920 with a son Primo 6 yrs old, and she also came with an Elena Chini. Luigia's father is listed in the manifest as Timoteo Chini who lived in Val di Non Segno. There are so many Magnanis listed in the Ellis Island manifests, and you seem pretty proficient with researching your ancestors that I'm not sure if you would have already found this. If not, I hope you find this helpful.
One more reason why I found the Magnani name so interesting is because not only were they coming to the U.S. with Chinis, but they were coming here with Michellis as well. Michelli is my mother's maiden name -- my grandfather Robert Michelli married Rose Chini. Small world!
Sorry for such a long reply. I would like to converse about about this more and see if we could help each other with more info. If you are interested, please let me know. The Ellis Island website is www.ellisisland.org
. You have to register, however, it's free and you will find yourself going back again and again. After you register do a passenger search for Carlo Magnani. You might get more than one hit, but it has the date and that will help you narrow it down. Good Luck! Hope to hear from you soon.