This seems pretty simple to me. Are riombarans joining in order to gain a capital next to their enemy? No, apparently there's only one character so far. Was it built up with military infrastructure pre-secession to more effectively wage war before seceding? No. Is the new realm going to be a riombaran copycat in diplomacy or forge its own path? Likely the latter. Did the planning of this secession start with 'we can gain a military advantage by having a new capital next to Enweil'? From what I've read here, I would surmise the answer is no. Is there IC reasoning/roleplay behind the creation of the new realm?
None of these answers seem indicative of strategic secessions to gain an advantage in a war that seems to have already been won anyway.
Remember, there is a difference between a secession during a war and a secession to gain a strategic advancement during a war.
