I hate to put it this way, but the odds of Chilwell staying fit for a season seems ….. low to me. And yes, Cucu has played lcb in a back 3 comfortably. I doubt they had never considered him prior to this; you just have a situation you missed on a set of targets to structure the team and are now going deeper on the list.
Many think Cucu would be an upgrade on Chilwell even if healthy, Emerson has apparently annoyed the staff with his play.
SO, you could possibly upgrade lwb and/or provide cover for the back 3 setup all in one signing, in a way that would give quality either direction.
If they are blindly throwing darts at a board, then they got really lucky.
I’ll believe it when it actually happens though.