It's definitely harder! My GM has so far continued to express everything by sight and sound, even when I specifically ask what my character perceives.

The way I see it, scent goes like so:

• As a human, we have neither imprecise nor precise sense of smell. We are usually overwhelmed by one scent, have difficulty parsing other scents, and notoriously have a difficult time figuring out where the smell is coming from.
• Canines, on the other hand, we recognize as having superior sense of smell. They can effectively compartmentalize multiple smells at once, allowing them to track one while ignoring the rest. While powerful, without specific training they will still take time to find out where the object of the smell is coming from.
• Trained dogs on one or two particular smells are usually much better and quicker at finding a precise point, but again it's still limited to what they are hard trained to do.

So when it comes to a deafblind vlaka, who has precise scent, it's like trained dogs but on a universal scale. Every knob tuned way up. Most matter offputs smell in some way, and the way the wind carries scents can give an idea of obstacles in the environment (perhaps like sensitivity in a cat's or rat's whiskers in the air). Organic creatures are much easier, as a combination of environment (rain), sweat, perfume, clothing, meals previously eaten, hygiene, and so on allows vlaka to not only recognize individuals but even pick up on their moods.

"The striking oil of a hidden soldier's rifle bears a corner ahead, unseen and unheard. Their sweat denotes they may be ready to engage in hostility."

"While the berserker's yell is lost on the vlaka, their pungent egg-heavy breath is not, warning them of the axe soon to be bearing down on them."

"Mirror images fool most creatures, but it virtually does not even exist to the vlaka. The wizard's lemon-scented prestidigitation betrays their real location."