A few things here: on Steve's Map, Elde Island appears to be about 60 miles from the Empire at its closest, which is more than twice what Paarfi says (perhaps Paarfi is using some other measure of mile?). Second, I don't understand what he means by "across the neck of the northern 'staffhead'" based on Steve's Map; there's nothing about the shape of Elde that suggests it has a "neck."
Having said that, the dimensions given ("about two hundred miles across and ninenty or ninety-five miles from the mountains to the coast" does match up rather well with the northernmost section of the island on Steve's Map, so I drew in a mountain range east-to-west across the island at that point, with a river flowing from the mountain range to Salute.
Illista travels across across this channel in The Lord of Castle Black:
Since the cove is 20 to 25 miles from Ridgly, and Cliffside is less than 5 miles from there (which I guessed meant 4 miles), that means Cliffside is anywhere from 16 (if the cove is 20 miles from Ridgly, and Cliffside is northwest of the cove) to 29 miles (if the cove is 25 miles from Ridgly, and Cliffside is southeast of the cove) from Ridgly. I put it right in the middle, or 23 miles to the southeast of Ridgly.
From there, they travel "up the coast" to Merinna; I think "up the coast" suggests to the northwest, but that's the opposite direction from their eventual destination near Hartre, so I put Merinna about a half a day (25 miles) southeast of Cliffside along the coast.
From Merinna, they travel inland to go to Hartre where they intend to eventually rendezvous with Kana. Hartre is also on the coast, so my guess is that they traveled inland to the Great Northwestern Road (which runs between Lorimel and Hartre).
I drew a road connecting Merinna to the nearest point of the Great Northwestern Road.