What an intriguing post.
Just a few thoughts.
I don't think there is a specific answer for the way to 'train' your hypothetical person. What might work for one person could be completely ineffective or even negative for another. - people are individuals.
The answers you seek are the answers evolved by all of us as we adapt to the specific norms of all the communities we are involved in - family, friends, work,culture,interest, etc. For each person this chain of communities can be ever changing, incredibly varied and with different degrees of importance for different needs.
Sometimes the answers involve acceptance, mimicry, knowledge, understanding of new ideas and sometimes there are no answers compatible with a particular person and a particular community.
There was nothing cheap about Markycielo's post number 10.
His idea of having opportunities which can be developed and the person adapting and evolving in their own way is far more respectful of the individual than 'training' which has a kind of dictatorial overtone to it.
His idea that the hypothetical person is already normal is spot on. He points out very well that 'normal' is defined by each particular community.
'and I want to know if it's really possible to culture him without that fostering care.'
You don't have to 'love' your subject but you do need to care.
Are you saying the city culture is unloving/uncaring and your subject needs to be the same to fit in? If that's the case then it's the city culture that needs the 'training' and the subject should have nothing to do with it.