The Equator is in line with Gaia's name on the map (the green one in the middle)

If you're okay with sharing, then its ok. I noticed Calxus has territory overseas, so maybe HSE owns Wesern Calxus and KoA owns Eastern Calxus or vice versa, which is especially likely if the HSE are new to the seas. 
I doubt the relation between these two will be cordial, since HSE is a highly religious, somewhat faithist nation. Close borders will spark tension.
If we will share territories, no more than two nations a territory.