Great that you are going to visit and seeing her basenjis first hand. That's one thing I admire about Jean - she is going to do what is best for her dogs and it is great that she is so straight forward - she wants it to work out for the dog and the person adopting. She may know of other breeders that have adults available - ask her when you visit with her - if you still think that basenjis are right for you. They aren't for everyone - my friends constantly ask me - you like these dogs why? hahaha
And just so you know and so you won't think it is uncommon, I have 3 that I would say would need a basenji experienced person, my 4th (which is Jean's boy, Ozzy), would probably be the perfect dog for anyone - he's almost an impostor because he is such an easy basenji - but I deserve him after my other three. 😉