With Season 10, there are a number of Characters that have a classification other than "character" (see: all of StarCo for example). Do these models count as veteran troops for classification purposes?
Nope. Character classification counts as Veteran. If not a Character classification, then it is irrelevant. I believe part of the intention is to treat named Mercs differently to named Characters who exist within the military hierarchies of their respective factions.
The issue isn't just with Mercs though, Dire Foes 6&7 are not classed as characters either, for example.
Army also treat these characters as Characters with regards to Soldier of Fortune extra disallowing Characters from being duplicated.
So is this working as intended then? B/c on pages 65, 67, and 68 of the current profiles .pdf, you have various non-character characters listed under the section heading of characters. Notably, this is not all of the mercenary troops you might think of as potential characters (for instance, scarface and cordelia) which are sectioned off differently.