Exactly. If you use the standard version of the Universal one-armed hanger, which has less offset, the cable will be off-center and too far to the non-drive side. I'm not aware of anyone else who made a hanger that works for the Cinelli-width seat post bolt. Other two-arm hangers aren't wide enough. Modern ones that hang from the center of the seat post bolt won't work because the bolt snugs up directly against the seat post. I hear that Spence Wolf used to bend the sh*t out of Mafac hangers or some such to fashion a working hanger, although I have not seen one, pictured or in the flesh.

Cino Cinelli was a great designer and I love his bikes, but there are times when his proprietary designs are a bit of a nuisance.