I enjoyed this a lot! Setting aside the case of Kawaii making Tadano her goal in life, I can relate to working towards a goal for a long time, just to find out it didn't work in the way you imagined. For many people it's a devastating feeling. Soul-crushing even. Sometimes you can just try to make the best of it.
In Kawaii's case, she can now realise that even though she worked towards a goal impossible to attain, she has made friends, improved herself in many ways and even forged bonds to a new family. All that is not useless, it's great that her pursuit for Tadano lead to the life she has now. Great! Just a great piece of story worth reading about!