Rosette, Utah is located about six miles west of Park Valley, Utah. It was apparently even less important then Park Valley was. Even the LDS’s Family Search website has no information about Rosette. The only piece of info I can find is from Online Utah which says:
“Rosette is a small ranching community five miles west of Park Valley. Jonathan Campbell, the first postmaster, named it in 1871 for the wild roses in the area.”
I do not remember seeing any signs of habitation when I drove through in 2010.