A while back, a fan, Jake Pitcher, thought a mileage map would be helpful, and posted a Google Sheet of distances.
And recently, another fan, Joachim Deneuve du Surlign. has produced an interesting "world" map here.
This new map contains longitude and latitude and even best guesses of the relative positions of the 7th Sea geographic regions explored so far.
TAJ-07: Technopriest And Justicar Of 7thSea2e