NHF – new heroes for Heroes V 3.1.

Hmm, sorry, but then it's just a convention of the game mechanics.
Counterspell isn't a spell at all, don't get it mixed up ;) It's a special ability.
Hmm... it seems to be clearly stated that the diplomatic mission was to Silver Cities, right? The mission was led by Godric, Duke of Unicorn... the original five, the "Diplomat" scenario.

A spell is any active action from the book that affects someone. Counterspell (SPELL_ABILITY_COUNTERSPELL - the developers' original name) is one, as are reinforcements, etc. It is also a perk. The problem with Vincent's biography is that the player already needs to know that Godric is the Duke of Unicorn (I didn't know or forgot, which is why the mix-up happened) - that's the downside ;)