The Hobyo Sultanate did not include all of Mudug and Galgaduud, neither is this sourced from Cassanelli nor Luling.
See the maps of the Hobyo Sultanate below.
Hobyo was not inhabited by the Hiraab or Hawiye in the late 19th century due to its changing terrain which became uninhabitable. See below. Source is from an easily accessible book called The Earth and its inhabitants in 1890 page 411
I also have proof of the partitioning of the Hiraab Imamate from an Italian source in 1899, translated. It started from Ras El Hur (south of Hobyo) all the way to Merca. See below images.
Translation
