@NotFunStuff
Emperor as head of state of the Someforth Empire? Sure absolutely makes sense.
Viceroy for the leadres of various 'countries' doesn't work unless the monarchy of those countries have been deposed. Viceroy has a specific use to indicate therepresentative of the soverign who is governing the territory in the soverign's name. (ie: Governed by the crown and not the feudal lord). Viceroy is not a noble rank anyway. The term Governor is probably better and more universal for the person administrating that territory unless theres a noble rank specified.
Duke lead Duchies and may have other lesser nobles under them (Counts, Barons, etc).
Generally ranks of nobility are somewhat like:
Monarch > Duke > Earl/Count > Viscount > Baron. Sometimes there are french noble titles like Marquiss or German ones like Margrave in some manga too.
The lord of Canale is probably a Count or Viscount. The Japanese aristocracy is a little different and not directly translatable but looking up the Kanji thends to give you english equivalent terms that make sense.