Regarding the jedi masters’ intentions in ROTJ, I had never given it much thought to be honest. I don’t think I even realised there was a debate until recently. To me it was clear that both Obi-Wan and Yoda wanted Luke to kill Vader, for several reasons:
Obi-Wan says that they have already lost when Luke says he can’t kill his own father. He then shuts down the idea of redemption when Luke suggests there is still good in Vader. This would be some really bizarre reverse psychology if Obi-Wan actually intended for Luke to somehow stop Vader peacefully. Also, this is not totally solid as it was cut, but in the ROTJ script there is more dialogue in this scene and Obi-Wan says quite explicitly that Luke is to ‘destroy’ Vader.
Yoda’s intentions are less clear in dialogue but I still get the impression that he wanted Vader to be killed. He says it was ‘unfortunate’ for Luke to find out Vader was his father, and considers the knowledge a burden. This could really only be the case if the intention was for Luke to kill Vader. If the plan was for Luke to somehow turn his father instead, knowing about him in advance would have been more of an asset than a hindrance.
Lastly, the dramatic tension of the film hinges on Luke believing in Vader’s redemption when literally no-one else would. He manages to force a resolution without resorting to killing, defying all expectations in the process. It’s bizarre to me to think his mentors secretly wanted the same thing, and they just refused to say that or worse heavily imply the opposite.
I addressed that already. He’s saying that Luke has to be willing to kill him if it comes down to it. He doesn’t intend him to stop him peacefully but we don’t know that he intends him to stop him at all. They’re sending Luke to Vader to face his fear and become a Jedi, not to kill the enemy faction’s leader and win the war.
I don’t see how that follows with the burden. It’s unfortunate and it’s a burden because it’s really harsh to find out that your father is Darth Vader regardless of what you do. It’s painful. It never even occurred to me that he would be saying that strictly in a tactical sense of how Luke is going to fight or neutralize Vader. That’s not how he delivers it.
The dramatic tension comes from a lot of things. There’s the Battle of Endor, of course. On the other side it’s mainly about Luke believing in Vader’s redemption while Vader himself doesn’t. Obi Wan and Yoda might have a pessimistic outlook on that but they’re not telling Luke not to try. They never explicitly say that Luke needs to kill Vader and not to try anything. The important part is that Luke goes to face Vader again regardless of the outcome. That’s what is holding him back from being a Jedi, which is what Yoda says.
They’re not sending Luke to simply face his fear. Confronting Vader is obviously incredibly dangerous, and something with very limited potential results. Obi-Wan believes Vader is beyond redemption, so what do you propose he’s hoping will happen when Luke confronts him, if not to stop him? Obi-Wan doesn’t say Luke has to be willing to kill Vader, Luke says he can’t kill Vader and Obi-Wan says that means they’ve already lost.
Yoda is pretty tactical tbh. He kept Luke in the dark about his father just as Obi-Wan did. He even deflects when Luke asks him in ROTJ, only answering when Luke insists. They both choose to hold on to that secret and let Luke fly to Cloud City unaware. They were both far more concerned with Luke being fully trained than him knowing the truth. When questioned why he thought it was ‘unfortunate’, Yoda says it was because Luke had rushed to face Vader, and wasn’t trained. He never really speaks about it on an emotional level.
They never explicitly say ‘kill Vader’, but it seems the most logical conclusion to draw from what they do say. There is a lot of stretching required to conclude they didn’t want this outcome, and they could have been much, much clearer about their intentions if that was the case.