I’m currently writing my Master’s dissertation on the topic of stream-entry in the early Buddhist texts. One of the things I am questioning is precisely the synonymy between the arising of the dhamma eye and stream-entry, because I realised that those situations in the sutta almost never (to the best of my knowledge at the moment) use the language of stream-entry. I think I have it somewhere in my notes that perhaps there is an instance in which after the dhamma eye one is said to have abandoned the three fetters and therefore become a stream-enterer, but there is another one in which the result is a higher attainment, and most of the times (almost always) we are not told. It simply doesn’t use the language of the four stages. Instead it tends to be related to taking refuge and becoming a lay follower, and sometimes this comes first and later the dhamma eye arises in that person, and some other times the arising of the dhamma eye causes someone to take refuge and become a lay follower.
I obviously cannot go in the full details of what I’m writing, basically because I should be writing my dissertation just now LOL But it might be helpful to remember that the treatment of the stages as a momentary thing belongs to a later period. In the early texts something like stream-entry is not a moment or an insight or a meditative experience, it is fundamentally a condition, i.e. being a stream-enterer. One of the main definitions, for example, is that a stream-enterer is anyone who has full confidence in the Buddha, dhamma and sangha and has a virtuous behaviour.