What they have achieved is not psychic and spiritual transformation but psychic realization and certain experiences in the spiritual realm, mostly in the spiritual mind, such as realization of the Self, experiences on the intuitive planes, certain revelations etc. This is different from transformation which implies a radical change in the fields of lower nature as a result of and influence of the psychic and spiritual realizations.
To make it clearer, there are these three things. Experiences mean coming in contact (direct or indirect) with the soul or realms beyond the mind. This contact takes place in the domain where these truths reside. Realisation means being established in these realms. Thus for example psychic experience and realisation means knowing oneself immortal and a portion of the Divine and hence no more mistaking oneself for the limited ego personality. It leads to a surge of intense bhakti and faith and surrender. But this does not necessarily mean a change of the lower elements. But psychic transformation would mean luminous Godward thoughts in the mind, sweetness of Divine Love in the heart, refinement of all emotions, passions and movements of life turning them Godwards. Even a change in the body so that it makes the right movement and is open to the Divine Influence.
The past Yogis didn’t know about these things, these distinctions, let alone supramental transformation etc because their seeking for God was limited to personal mukti and at best helping others gain this liberation. They never thought of changing the nature, in fact considered it impossible. If you read their life in detail you will see what it means.
Affectionately,
Alok Da