This is a rough call... Despite how much Olive Branch seems to want to tank negotiations. Are we willing to risk war so soon? Taking the deal, despite how bad it is, is still bearable, a huge pain, but bearable. And would end this as quickly and peacefully as possible.
That said... Everything about Mareatona makes it really clear that these idiots need a wake up call. We pay the ransom and it's pretty clear that this is all going to happen again. And will keep happening until Mareatona learns to respect potential threats.
I'm more leaning toward 'no', mostly because we actually have a lot options here, especially with the shake up between their Queen and the Wealthy Nobles. If we kill the Nobles holding our citizens prisoner, Queen Mareia can start consolidating her power in the vacuum, framing the whole thing as a 'You should have listened to me~' from her.
Plus, we have the list of Targets and Hostages. pulling off a series of assassinations seems actually pretty plausible, especially with how well our Spys have been doing. Sneaking in a few Orichalcum clad assassins to steamroll any magical defense they might have and cleaning house sounds well within our purview.