Dear KS, a bit of kindly advice: stick to Hindutva. Hinduism is deep, and some of us are out of our depths in those deeps. This is meant with sincerity.
Count the heads on the statue of Avalokitesvara. Count the three-headed structures as four heads, and the topmost two as single heads. This is the eighteen-headed form of the Bodhisattva. If you have the patience to count her arms, you will find a hundred. This is the Chandi manifestation of this Bodhisattva.
Many Hindu deities were represented in parallel in Buddhism. In fact, there was an erroneous thought that Avalokitesvara himself (as male) was a form of Isvara, Siva, since that is what the 'sandhi' seems to imply from the rules. Actually, there is a form of the name, Avalokitasvara, which is legitimate in Sanskrit, and which was the original form. The Chinese form was earlier thought to be a distortion, based on misunderstanding. It is now known to be an exact and precise translation of Avalokitasvara, he who hears the sorrows of the world. It was because he heard the sorrows of the world and his head burst into eighteen pieces. The Buddha then made him eighteen-headed. He then fought to bring salvation to all, and faltered, so the Buddha gave him the many arms and weapons of Shakti, in her Chandi avatar.
Buddhism and Hinduism borrowed and exchanged a lot in late mediaeval India, and Tantric forms of both exist. This was largely the theological milieu in which Vikramshila, Nalanda and their three sister institutions flourished, this was one of the forms that the very learned Atish Dipankar took with him when he revived Tibetan Buddhism. It is evident from the forms and aspects in which the Bodhisattvas were visualized in China, and in east Asia, that there was a continuing and lively exchange in those centuries.
Just for the record, not a single one of them is a 'Vedic' deity. They are certainly in one manifestation Puranic Hindu deities.