Exitzero, did you just reply to yourself in the 3rd person? LOL
Now that you mention it, I think I had heard or read somewhere a number of years back about the same thing with GL stating 3 years had transpired between each movie which lines up with the actual time between the movies themselves releasing and probably why I misread the BBY/ABY times as I already had a preconception of the time frames.
In regards to your second post, I believe Yoda only said it in that fashion to try and impress upon Luke how unready he is to face Vader at that time.
Where in ROTJ Yoda knows he is ready now or as ready as he’ll ever be in the time they have left to defeat the Empire before all is lost, so he essentially gives the confrontation his blessing but knows as well that it will be the biggest challenge Luke will have ever faced and if he comes out of it alive and still on the light side, then he will have mastered control of his mind and emotions in the face of that massive adversity and facing the Emperor and his father of all people, essentially proving his worth to take the title of Jedi Knight (not Master mind you, but the first level of “Jedi-hood”) regardless of the time it would take under more normal circumstances and the fact that he will be the last of their kind and so needs Luke to become a Jedi to keep the flame of their order alive and pass on what he has learned. He could not do that if Yoda told him he hasn’t met the prerequisite 25 years of constant training under another Jedi and that there’s no one else left to teach him now anyway 😉