About this line: "it will make things like ransoming your king interesting" - Is this an allusion to allowing the realm to pay the ransom for the imprisoned characters?
No, its an allusion to thinking about other options then the random escape chance and just waiting until it's over. That is why I put the max terms extremely high intentionally. I want people to NOT wait them out, but figure out ways of getting out earlier. Ransom is just one obvious one. Making a deal with the enemy judge is another. Prisoner exchanges are a third.
None of them require new game mechanics.