[Fededorbprago]

'sattā opapātikā' is part of mundane right view, per MN 117

in mundane language (conventional truth), 'satta' means 'being' or 'person', such as in Bodhisatta (Bodhisattva)

in dhamma language (ultimate truth), 'satta' was explained as follows:

Any desire, passion, delight or craving, Radha: when one is caught up there, tied up there, one is said to be 'a being'.

Satta Sutta in the mundane right view (per MN 117; MN 60, etc) sattā opapātikā is connected to the other aspects of mundane view, namely, fruits of kamma and the other worlds

so, imo, 'sattā opapātikā' means due to an act of karma, the result can be immediate/spontaneous