TheBoost idea that I like a lot is to make it clear that Luke spent a long time with Yoda for the last year or so. If he never saw Yoda since empire that means he was only trained by him for few days. Even with the best skills Luke could not became so powerful with so few training from a master IMO. I like the idea that Yoda never wanted to tell him the truth, but once he feel that he's dying, the truth needs to be told. Problem is it needs dubbing Yoda or finding a workable line from Hamill from another movie. (like "I need to ask you again" or something like that)