Tattva vadi means those who can speak about tattva siddhanta nicely without having direct realization about that. But those tattva vit puruṣas—they can speak about all those tattva vijñāna topics out of their direct realization power. This kind of tattva vit realized Sad Guru can give us tattva-jñāna together with full realization power—provided we can fulfill the following three conditions written in Śrīmad Bhagvad-gītā—
tad viddhi praṇipātena
upadekṣyanti te jñānaṁ
jñāninas tattva-darśinaḥ (Bg. 4.34)
Just try to get tattva jñāna by approaching a spiritual master who is tattva vit himself. Inquire from him honestly with submissively attitude and render service unto his lotus feet–sincerely. The self-realized tattva vit purusha can give tattva jñāna inside your heart.
Shri Shyam Das Baba