I do not know if its allowed to suggest here but would be nice to see changes also in L3T diplomacy.
Yes, sure it is the right place to go about it
So i always thought Vanilla. Diplomacy especialy with that what includes money were little silly and simplistic.
So I think if you imprison someone you dont just demand cents from captures but you demand a ransom. Why ask from courtier only 10 gold if he has 200, or why to ask duke only 145 gold if he has 700. So my idea would be you can deman more gold from ransoms, but more you demand, if you go insensible you get prestige or piety hit from that. But you can clear you enemys out and even force landed charcters to take loan to pay for they release. Ofcouse there could be change they just refuse you and only accept normal ammount. this would give real value to heirs. To extention if character does not have money he could give you titles or claims and also suffer opinion and prestige hit in they realm.
Diplomacy is a tricky part because some of these are semi-hardcoded, if not completely. For the example of ransoms, it seems that if we want to do something about, we need to deactivate completely the vanilla interaction and so coding a whole from ground. Having well done and balanced could be huge work. CK2 is not very kind when it comes to flexibility, scaled_wealth behaviours as example of how it can became wonky.
About the specifics, for gold, you don't necessary know how much someone can offer, unless the prisoner or someone of his court made the offer, but I agree taking the rank and circumstances into account should be nice.
Claim as a trade of could be nice, even though it should be part of peace deals, but it could be done in this scope sadly.
Consequences when the character comes back home is also a good idea, being captured may impact legitimacy, views from others, authority...
Not exactly the same, but L3T provides an additional way to deal with your prisoners who are religious enemies, sacrifice them
I can't promise I'll work on this, at least not soon, but don't mind getting into something more detailled. I guess we can make a trade of gold/rank, claims, artefacts etc. with some kind of negociation dialog (chosing what to ask for, counter-proposal, chosing what to offer). +consequences once back to home, not really sure how to design it though.
war rep with realms you have defeated would be also be nice diplomatical adition. War rep would be like forced monetary tributary, what breaks automatically when time is up. War rep should include also extended truce. Idea between wars should be also prestige based. If you defeat enemy you could deman almost everything. But each demand what goes over sensibilty demands more prestige and maybe gives even general opinion penaltys.
Modding CB is quite a hell, I'll avoid diving into that
In general, I'm trying to not alter too much base vanilla systems in this mod.
Also suggetsions with floods and draughts. WOuld be nice if there is possible to build or develop some syetems like irrigation systems to handle draughts or dams to handle floods and make impact lesser or less frequesnt.
I have some plans to extend a bit the natural phenomenas flavour, these could be some good suggestions.