How exactly does the vow to renounce war work? Was it as simple as Karl just told Ymir that from here on forward no royal blood family member can use the titan powers for war/the rumbling. If so how did Marley explain to the public that they could send eldians to paradis but not start the rumbling?
Does the vow to renounce war did it simply work just like that Karl Fritz went to the paths and explain to Ymir from now on no royal family member can use the founding titan powers to wage war or do the rumbling. That's why any non royal who held the founding titan could only use contact with a royal to activate the founding titan's power circumnavigating the vow. So if that's the case then that plothole is easy to explain away.
However my question is if in universe the marleyan people are aware of the fact eldian are sent to paradis and turned into titans how does that not violate the threat that king karl fritz gave saying his paradis undisturbed?
In the episode where there are flashbacks of reiner journey to the island with berholt and annie he mentions marleyan scientists said they found a loophole.
My best guess is that in universe king karl fritz threat was believed but as far as the marleyan public and world were concerned that meant clearly and obviously non eldian factions attacking paradis island.
So in universe the plothole with how karl fritz threaten the outside world but was believed only extended to mean to the people of the world as clearly and obviously non eldians such as marleyans or others coming to the island with boats and ships and siege weapons like catapults, battering rams or helepolis.
And we know that not all Eldians left for paradis. So likely Marleyan scientists who were in the dark like the rest of the population assumed to their knowledge as far as they knew the Eldians on the island didnt have their memories erased and eldians on the mainland still posed a threat the king only meant non eldians. That's mean using the titan shifters in their posession they could pose as continental eldian factions attacking the wall therefore instead of causing the rumbling would at worse just provoke a swift response from the founding titan.