How important are good reccomendations?

How much influence do they have (especially ivy leagues. Especially Columbia)?

Look at their CDS. Nevertheless, good LoR may not rescue a weak application, while a bad recommendation would kill your chance.

I assume a good letter that provides clear that understanding of you as a student would be quite helpful. The letters are a means of telling the school about you. Do his is good. You don’t want some flowery letter extolling your greatness. Just something honest and helpful.