Hi Sarah, Alberto
S: Yes, hadaya is a synonym for citta, the innermost nāma, manāyatana
This is not to be confused with the subtle rūpa, haddāya which arises in a group conditioned by kamma and is the vatthu (base) for all cittas in this realm aparat from seeing, hearing, smelling, tasting and touching. As a subtle rūpa it's dhammāyatana, the outer āyatana.
A: Yes, that's right, thanks Sarah (I've just checked the Pali spelling, is the same for both, as a word for citta and as vatthu rupa, and it's also hadaya, the heart, as the 11th "part" of the body, kesa, loma, nakha...)
Lukas: I only referred as innermost, citta is hadaya. Innermost. I didn't refer to the kind of ruupa that is hadaya. I only referred to the two instances of cittas in Vibhangapali. that cittam pandara and hadaya. So pure and innermost. And also do not confuse hadaya, innermost <citta> as ajjhatta/bahiddha that is mentioned in satipathanna MN.10 or Vibhangapali I.Khhandha instances. So do not confuse the citta hadaya innermost or most inner with ajjhatta like internal referring to self.