Wow, thank you so much for your replies! I'll make an offer and see where it goes from there. I'm all in to upgrade some parts in the long term. For now, I just want to make sure the components are alright and that the frame looks good. I'm more or less 5'7, so a 54 cm frame is pretty much my exact size. There's another Colnago bike I'm looking into, but it's a 52 cm frame and I'm afraid it will be too small for me.
I'll keep you updated!