"Woo Sau" -- Some call this guarding hand but I think they pronounce it wrong. It is not Woo (Wu) but should be "Woah Hand" because that is the sound my parnter makes whenever I use it.
"Bong Sau" -- Some call it Wing Hand. Another miss translation and mis-pronounciation. I call it "Bonk Sau" because I collapse my parter's structure and "bonk" them at will.
"Lan Sau" I agree with the pronunciation but not the spelling.
"Lawn Sau" spelling encourages the accurate pronunciation while revealing an important Wing Chun Secret -- that the arm should be like the bar of the handle of a lawn mower.
Keep training and my regards to Sifu and Grandmaster Chu Shong Tin for their efforts.