when I mentioned “I think it’s not really correct as of the example of that person who was Sotapanna but didn’t believe it even if Buddha said so” – I mean that one of your posts about Sotapanna had this story from the suttas, it’s from a different one. :)
“Mahānāma was a wealthy person who was related to Prince Siddhartha’s family. The Buddha told him that he had attained the Sōtapanna stage. However, when he was engaging in his business activities, he often got frustrated and angry with his servants and yelled at them. After such an episode of outburst, he would think, “if I am still able to become angry like this, I must not have attained the Sōtapanna stage yet.” So, he would go to see the Buddha, explained what happened, and ask whether the Buddha was sure about the declaration. He still had doubts about his attainment of the Sōtapanna stage until the Buddha confirmed it for the third time; see, “Paṭhama Mahānāma Sutta (SN 55.21)“”
Saying that for example that every Sotapanna will know the way to Nibbana seems not consistent also
“What sort of person is one who may be guided (neyya)?
The person for whom penetration of the Dhamma comes gradually by means of recitation, questioning, proper attention, and by serving, cultivating and waiting upon kalyānamittas is called “one who may be guided.”
so if person falls into category it seems one will not able to attain Nibbana on it’s own even after being Sotapanna even above.