Haven't watched much of Lengelt, but from what I've seen I didn't find him to be very impressive. Yes he was great against us, but I don't think he is that good consistently
Also even if we were in for him, he would have chosen Barca ahead of us
Barca have a better team than us plus he won't have to move to an unknown league / country. He's settled in Spain and happy there, so why would he move
We would likely offer him more legal tender than Barcelona.