I guessed the tropical village of Southpoint was located at the southernmost point of the Empire, which appears to be almost due south of Hartre on Steve's Map.
The Barony of Halfwing
I guessed that distance was as the jhereg flies. I drew a circle with a radius of 80 leagues (240 miles) and located Halfwing where that circle intersected the coast to the west of Adrilankha.
Roads West of Adrilankha
There is a road between Hartre and Adrilankha, and I think it has at least two names:
Lower Kieron Road also appears to run west of Adrilankha and goes at least to Barlen's Pavilion:
Since Barlen's Pavilion is near the Generous Wood:
And there are forests to the northwest of Adrilankha:
I believe Lower Kieron Road actually runs northwest of Adrilankha.
As for the Northgate Ferry Road, since the attack was expected from the west, I believe this road runs west of the Adrilankha River, and is most likely the road described in the Special Tasks portion of Tiassa:
In other words, two miles from where Vlad was found (direction not stated), the road splits, with one road running to Favintoe Market, the other to Junglebrook. They take Vlad to a place near to Favintoe Market, and from there a messenger manages to run to the Palace in Adrilankha in half an hour.
The farthest any human being has ever been recorded to have run in half an hour is
about 10 km. While it's possible Dragaerans are faster than humans, this particular route was also not over a track course, but the combination of a road passing through a jungle and a bustling city,so I am confident the Guards are well within 10 km (6 miles) of Adrilankha, and possibly even just outside the city.
Later, Khaavren travels from this same headquarters near Favintoe Market to where Vlad was found:
First of all, note that he says Vlad washed up on the west bank, and the nearest bridge is an hour away. That puts all of the locations mentioned in this section of Tiassa to the west of the Adrilankha River.
Second, it appears that horses cannot canter or gallop for more than a few miles at a time, so it is likely Khaavren was moving at a trot, which is about 8 mph, so at most, Vlad was found 8 miles north of Favintoe Market, which is, at most, 6 miles north of Adrilankha.
Back to the original trip, 2 miles from where Vlad was found, the road splits. Since we now know Favintoe Market is south, the split that leads to Junglebrook probably runs west. There's no indication given for how far away Junglebrook is, however, so I left it off of release 3.
Vlad claims the last place he could remember being was yet further north of where he was found:
Vlad was 9 or 10 miles north of Profimyn, but found 20 miles south of Profimyn, which means Profimyn is about 10 miles north of where he was found.