To clarify, the end of a Mahakalpa = the beginning of a Mahapralaya.
The end of a Mahapralaya = the beginning of a Mahakalpa.
You said that at the end of a Mahakalpa (beginning of a Mahapralaya), Arhats, Pratyekabuddhas, and Bodhisattvas below the 12th Bhumi, etc. revert to the Basis.
So my question is what about at the end of a Mahapralaya (beginning of a Mahakalpa)? This is when the Basis begins to stir right? In other words, the period of 'repose' between Eons is just that, a period of 'repose' (Mahapralaya), during which, as you've said, Buddhas who have not reached full Enlightenment revert to the Basis. And at the end of the Mahapralaya is when the Basis begins to stir signifying the beginning of a Mahakalpa (?)
The questions asked in my previous post are in the context of this understanding.
In other words, we've discussed what 'happens' with Buddhas who have not achieved full Enlightenment at the end of a Mahakalpa, but we haven't discussed what 'happens' (or what could 'happen') with them at the end of a Mahapralaya.
Although I'm sure you've written about this in at least one of the many, many (

) discussions here regarding the Basis.