@Azeloth agreed, but re balancing all events is quite the task

My personal opinion is what causes unbalance in game is scaled money. Where some common artifact cost a whole decade of somelord income. Or When you bribe courtier with ammount of money you could build multiple buildings. Addition to that Game spawns alot of money. Often in decisions where someone gives you ammount of money and they actually dont lose it. So game spawns alot of random money. Ransoming itself is not that bad. Like you said everyone has they own opinion what needs Balancing.

@Ēarendel lol what ?
that's not what the mod does, on the contrary
it make it so the max you can get at 30 Diplo is what Vanilla would have given you
some a peasant will be w/e a peasant's worth in vanilla at 30 Diplo, half the value at 15 Diplo, etc

Is some peasant bumpkin really going to cost 100 gold with 30 diplomacy?

I can't, but i can say that if recall your files correctly then you should have the same issue.
The issue being - if you are trying to ransom a third party (say, your child), then UI cost in the option itself is different to the actual cost, because those are shown before scope:payer is set and are listed from POV of secondary_recipient, thus, counting THEIR diplomacy, not YOURS, so the cost is different.

@Captain SSmolleTT "With my thing the loc kinda breaks when ransoming a third party (i assume this might be an issue in your mod too?)" => send me a screen in PM ;)

With my thing the loc kinda breaks when ransoming a third party (i assume this might be an issue in your mod too?)

I didnt get what you were saying at first but now after testing it a bit yeah, i didnt account for that somehow. Oops. Anyways here's what i came up with , except i wanted it to also increase ransom costs if you're way better. You can prob change the offset (add = -1 part) to be the same as max and it will work just fine for your case:

multiply = {
value = 1
add = {
value = imprisoner.diplomacy
add = 2 #offsets the values a bit so 1 vs 2 diplo isnt an x2 difference
divide = { value = diplomacy add = 2 }
max = 1.5 #range 0 to 1.5
add = -1 #range -1 to 0.5
multiply = 2 #range -2 to 1
multiply = 0.2 #range -0.4 to 0.2
#final range 0.6 to 1.2
}
}

@Captain SSmolleTT "(idk why would you have max 1.5 if you are capping it at de-facto x1 later)" because you might have your ransom value reduced by the comparison with the fixed value, say you have 10 and 20 is considered vanilla values => you'd get 50%
then you have twice the payer's diplo => up to 75% (1.5) to raise it up a little
and the check max is here to prevent going over vanilla if say
you have 20 diplo and 20 is considered normal => 100%
so even if you have double the payer's diplo => don't go overboard to 150%, cap it at 100 ;)

All that can prob be done as script value with no need to save anything inbetween.
You can prob do smth like this (idk why would you have max 1.5 if you are capping it at de-facto x1 later) throwing it at the end just of the value like you did:
multiply = {
value = 0.5
multiply = {
value = scope:imprisoner.diplomacy
divide = { value = scope:payer.diplomacy min = 0.5 }
min = 1
max = 2
}
}

this would start the ransom off at 50% of OG value and increase it up to 100% (so, vanilla value) if imprisoner's diplo is x2 of the imprisoned/whoever pays for them.

@Captain SSmolleTT I guess the best implementation could be :
this mod's comparison procs then :
divide imprisoners diplo by payers diplo (min 0.5 max 1.5) => comparison_factor_var
multiply gold by comparison_factor_var, max it to w/e the max vanilla value would be in the scenario (requires first saving the actual vanilla gold value before this mod's comparison procs)

Might add it as a game rule actually if I can come up with something that's satisfying

Fair, i played around with that for the past 30 minutes or so and didnt come up with anything in terms of dividing diplo, and getting absolute difference doesnt sound too cool either.

@Captain SSmolleTT well you're welcome i guess

as for the comparison I thought about it but ditched it because it was much harder to balance, as the player is more often than not going to have higher diplomacy than the target ; so to make the mechanism work as a nerf (which is also the goal of the mod), you'd need to sorta make it so that having twice the diplo as the payer would result in a normal amount, and also account for a flat limit as if you have 4 diplo and the target has 2, there still is no reason for you to get a lot of gold from that interaction
tl;dr, doable sure, a little more realistic perhaps, but quite a lot of maths for not much in the end imo

Although i think it would be a bit more interesting if it was dependent on difference between diplomacy of imprisoner and payer

Im kind of stealing that idea, thank you