Five major sins (anantarika kamma) and how to mitigate them?

I started to learn and read Buddhist teachings, everything is very logical and compassionate. However, there is one thing that makes me wonder and confused: as far as I know, all evil karma can be repented and overcome, so why are there some particularly serious crimes that cannot be cured? For example, killing parents, causing Buddha to bleed, killing arahant, dividing the Sangha. Is there any way for them to repent to reduce their sins? In case they realize their mistakes, do they still have the opportunity to practice and attain liberation? - If the 5 major sins I just mentioned cannot be mitigated through repentance, then does it contradict [this sutra](https://www.dhammatalks.org/suttas/SN/SN42_8.html) ?: "There's the case, headman, where a certain teacher holds this doctrine, holds this view: 'All those who take life are destined for a state of deprivation, are destined for hell. All those who steal... All those who indulge in illicit sex... All those who tell lies are destined for a state of deprivation, are destined for hell.' A disciple has faith in that teacher, and the thought occurs to him, 'Our teacher holds this doctrine, holds this view: "All those who take life are destined for a state of deprivation, are destined for hell." There are living beings that I have killed. I, too, am destined for a state of deprivation, am destined for hell.' He fastens onto that view. If he doesn't abandon that doctrine, doesn't abandon that state of mind, doesn't relinquish that view, then as if he were to be carried off, he would thus be placed in hell. - If someone accidentally creates the above evil karma without anger, will the result be different? I would be very grateful if someone could help me answer my question.