त्रिपिटके विश्वासटिप्पणयो

Source: TW

The shrI-guhya-sarvachChinda-tantrarAja is a tantra transmitted by the kAyastha gayAdhara paNDita to his Tibetan acolytes in the 1000s of CE. It seems to belong to the bauddha yoga-tantra class (for classification see: https://manasataramgini.wordpress.com/2009/02/16/nastika-notes-2/ )
and features some of the anti-shiva rants that typify the developing body of the later bauddha tantra-s.
It also seems to incorporate material from the kaula tradition but in a rather unusual form (Gentry’s translation from the Tibetan):

First, give rise to the divine pride.
Know that the DAkinI-s are the channels.
Know that the DAka-s are the spirit of enlightenment.
Know the locations of the chakras, the chakras themselves,
And their related practices.

The distance from the chakra of great bliss
To the confluence of brahmA
Is forty-eight finger-widths.
Each chakra is three finger-widths,
And thus the nature of enlightened body, speech, and mind.

The mention of the chakra-s and the brahma-granthi is a clear feature of the yoginI-kaula system.

However, this system features a chakra not found in that system:

Three spaces is the secret location.
Likewise, three spaces marks the chakra of awareness.
Four finger-widths is the location of hayagrIva.
Eight finger-widths is the location of Secret Guardian of Bliss.
… At the throat, in the chakra of enjoyment, One enjoys the six flavors.
Thus, rasanA is concealed in the chakra of enjoyment.
The hayagrIva chakra is concealed at the throat.
… To the right and left of the vowel letter of hayagrIva
Are two ‘a’ syllables, at the perimeter of which are nine petals.

What was the origin of this mysterious hayagrIva chakra? Was it from a lost H chakra system found in a vaiShNava or shaiva hayagrIva tantra?