Adiyen performed Bharasamarpanam two years ago, but till now could not avoid partaking prohibited food items and does not perform daily sandhyavandhanam as ordained. Are there any atonements to rectify these follies that are committed knowingly? Will this hinder the attainment of my salvation?

It is crucial to avoid such transgressions after bharasamarpanam since you are aware of it. Rectify such mistakes and follow the ordained austerities. Prayascitta prapatti can be done for such mistakes. These shall not hinder salvation.
Prayascittam is the way to rectify the sins that are committed knowingly. If one could not do prayashcittam, Bhagavan would administer lighter punishments and take us to salvation.