If there was ANY objective at all, it WAS to secure access to the Cagilan Empire. This was done, and is done.
Looking at the map, and taking in consideration the position and situation of Coria when the treaty was signed, the treaty is a failure for the norther realms.
Everything changes if we add that Eston ( Kerwin ) wants to start a friendly relation with Coria, it is a good treaty for that, limited military access and peace between both Realms. Regulus wouldn´t be surprised if Coria and Eston sign an alliance in the near future... but here is the main problem, Eston signed a good treaty thinking in her interests ... but not good enough for her allies.