Thank you so much! I had missed finding that immigration record, probably because her name is spelled Carry, so it didn't show up on my first search for Cerri. Since I did find the 1937 immigration record for Cerri, it never occurred to me to look for more. I just looked closer at the 1937 record and see that the fact that she visited in the US for 4 weeks in 1934 is in there.
This still leaves the puzzle of why there would be an alien case file for her from the 1934 visit when they didn't start those until 1940, which was well after her permanent arrival in 1937. Also, many of the bios I have worked on for other German immigrants were after 1940 and I have never before found any alien case file for any others. Cerri did travel (or reside in) Brazil in 1967, so perhaps when she returned to the US from there (I don't have a record of that entry) that was when the alien case file was created and picked up all her prior entries. Still, though, some of the others have traveled outside the US and returned in later years - some several times, without a record of an alien case file showing up at family search.