Turns out that each priest has a variance in the number of holy levels they contribute when calling.
Relatively small sample size but is strongly suggestive of holy ± 1 with equal (or almost equal) weightings.
A quick gather of a dataset calling with a single h1 at 49 rebirth points confirms that the requirement to return does not vary, rather that is entirely implemented in the holy level variation…
This is more complicated, but not unnecessarily so…
Pretenders can also heal afflictions upon being recalled, as detailed in afflictions