Well, I guess your right, the tweaks posted shouldn't be causing any new bugs or errors, just adjusting gameplay slightly with minimal impact. However, the opcode error doesn't seem to be breaking anything in the game, or causing any CTDs. Here's the error:
Script Error on OPCODE 23, Invalid Script Parameter ID: 2, Line NO: 2:
At script: diplomacy_start_peace_between_kingdoms
Now, this is the only error I've seen so far after about an hour of playtesting, and I'm certain it's nothing more then a dialouge error. It only appears in red once after you've paid a lord for peace (it isn't a walls of text), although it does happens everytime the player reaches a peace agreement. It's a little annoying, but it isn't a gamebreaker.
Also, keep in mind I wouldn't of posted if it didn't actually work for me. I'm currently playing a poor rebel lord operating out of Unuzdaq Castle, and I've been fighting off Rhodok invasions since I took the castle in the first place. Now, instead of waiting for them to initiate a peace deal, I can travel to a Rhodok settlement, speak with a neutral lord, and pay about 62,000 for a ceasefire (it's expensive due to low relations). Now, I don't have that kind of money at the moment, but the option is still great to have, and if I was backstabbed by the Khanate or randomly attack by Vaegirs again, I could pay them off so I'm not totally surrounded.
It might not be a very clean tweak, but it's easy to change and remove, has little negative impact (so far), and can help relieve some frustration when the player is trying to control his own rebel faction.