My lifts are plateaued for about two years. Maybe I'm too old to improve, 32... I'd like not to think that though
Nah, age is not a problem as long as you are not injured, trust me!
Now, the squat, interesting numbers. You did not tell us your weight, but whatever it is, 100kg full squat is too weak, both for an acceptable vert base strength level or for a strength plateau. On the other hand, 160kg parallel box squat is very good. And the difference to your 100kg full squat is chaotic, it should be something like 10-20%.
So, my wild guess is that full squatting is not your thing, not a rare case for tall guys. However the full squat should never be neglected, but it does not have to be a psychosis either.
So, comnbining all that data leads me to suggest doing something like that in the gym:
-Do 5x5 , ramping the weight and adjusting the depth too. So, with your numbers i would go like:
Warmup set 1 : 6x20kg(bar) , full
Warmup set 2 : 4x40kg , full
Warmup set 2 : 2x60kg , full
Working set 1 : 5x80kg , full
Working set 2 : 5x90kg , full
Working set 3 : 5x100kg , each rep as low as you can to NOT fail, so don't go full and fail, stop a couple inches higher and finish the reps/set
Working set 4 : 5x110kg , each rep as low as you can to NOT fail
Working set 5 : 5x120kg , each rep as low as you can to NOT fail
Repeat that until you can get the 5x100kg full. Then add 2,5kg to the full squats and 5kg to the half squats.
Repeat the process till kingdom come.
OR, split the squatting days to target both qualities:
Day 1 : Full squats : 3x5@85kg, add 2,5kg to the bar every workout until you can't get 3x5, we will talk again then.
Day 2 : Half squats : 4x3@140kg
Also, as a unilateral jumper you will need to give some extra attention to glutes and hamstrings work, i will leave raptor tell you more about that.
Don't take my workouts to the letter, it is just recommendations. Let's see what other people in here think...