not enough glue used to hold boards together
That can be good or bad. I did the entire upstairs in my house a few years ago, and the trickiest places 1 room and the landing, I did not use glue at all. I think this is the way to go.....I was conscious of all the pipes & cables in the landing and did not want to have to get a new floor if someone needed access to the pipes/cables.
levels not quite right so boards are springy in places
This is a problem with floating floors. It really depends on what they are floating on, an old existing timber floor, a new concrete base ??
I don't think he left it long enough to equilibrate (if that's the correct term) in the rooms before laying.
I really think this time is a few years..........I used semi-solid oak & it is still shrinking. This is less noticable where there is no glue as the gaps are dispersed. Where the boards are glued, they are pulling back from under the floorboards.
Warts and all, a timber or semisolid floor is so much nicer & healthier than carpet.
Rather that try & lift the whole floor, can you push the boards to one side (length ways) and replace the boards on the edge, the cut boards? Lift the skirting, tap the boards away from the wall, remove the last line of boards, typically cut lengthways, and cut new wider boards to replace them.
p.s. I am not the guy who laid the floor........