What happens if I free Jona Sederis?
Solution 1:
The Eclipse War Asset modifier is the same +50 regardless of how you resolve the situation. The only difference is the reputation you gain.
Release Sederis = +5 Renegade
Convince Sayn to take over = +2 Paragon
Convince Sayn to kill Sederis after she is released = none
Solution 2:
Sayn will choose to kill Sederis regardless if you free her or leave her in jail.
Solution 3:
Sayn (her second-in-command) will kill her and assume her place.
It's a matter of Paragon/Renegade choice really, it has no other influence on the game.