Unforgiveable/Unforgetable Past Abortion and Miscarriage

should we focus more in 8 fold path as core resolution and performing often chanting/praying without spirit tablet

8 fold path is the path of viewing in terms of not-self & dependent origination . Dependent origination is the view that the impersonal element of ignorance is the primary cause of unwholesome actions.

often chanting/praying is not the 8 fold path

obviously the example provided in the question is of a person/mind unable to practise the 8 fold path and abandon identity, personality & self-views

in MN 66, it is clearly taught a new born child has no self-identity, which therefore also applies to an embryo or fetus

yet the individual in the example in the question keeps concocting a personality view of the embryo/fetus and also of the aborter

the individual does not understand the doer of the abortion was the element of ignorance and that the embryo/fetus was mere elements (dhatu)

AN 3.61 says:

In dependence on the six elements the descent of a embryo occurs

From the sutta quote below, you can see that a person's actions while they were alive determines their outcome, and not rituals performed after death.

Also, please watch this video talk and this video talk on superstition by Ven. Ajahn Brahm. In SN 7, you can find many cases where the Buddha criticized superstitions.

In DN 2, we find that astrology, palmistry, divination, tea leaf reading, magic, geomancy, dream interpretation, making predictions etc. are considered "animal arts" and wrong livelihood for monks.

From SN 42.6:

Then Asibandhaka’s son the chief went up to the Buddha, bowed, sat down to one side, and said to him:

“Sir, there are western brahmins draped with moss who carry pitchers, immerse themselves in water, and serve the sacred flame. When someone has passed away, they truly lift them up, raise them up, and guide them along to heaven. But what about the Blessed One, the perfected one, the fully awakened Buddha: is he able to ensure that the whole world will be reborn in a good place, a heavenly realm when their body breaks up, after death?”

"Well then, chief, I’ll ask you about this in return, and you can answer as you like.

What do you think, chief? Take a person who doesn’t kill living creatures, steal, or commit sexual misconduct. They don’t use speech that’s false, divisive, harsh, or nonsensical. And they’re contented, kind-hearted, and have right view. And a large crowd comes together to offer up prayers and praise, circumambulating them with joined palms and saying: ‘When this person’s body breaks up, after death, may they be reborn in a place of loss, a bad place, the underworld, hell!’ What do you think, chief? Would that person be reborn in hell because of their prayers?”

“No, sir.”

“Chief, suppose a person were to sink a pot of ghee or oil into a deep lake and break it open. Its shards and chips would sink down, while the ghee or oil in it would rise up. And a large crowd was to come together to offer up prayers and praise, circumambulating it with joined palms and saying: ‘Sink, good ghee or oil! Descend, good ghee or oil! Go down, good ghee or oil!” What do you think, chief? Would that ghee or oil sink and descend because of their prayers?”

“No, sir.”

“In the same way, take a person who doesn’t kill living creatures, steal, or commit sexual misconduct. They don’t use speech that’s false, divisive, harsh, or nonsensical. And they’re contented, kind-hearted, and have right view. Even though a large crowd comes together to offer up prayers and praise … when their body breaks up, after death, they’re reborn in a good place, a heavenly realm.”

When he said this, Asibandhaka’s son the chief said to the Buddha, “Excellent, sir! … From this day forth, may the Buddha remember me as a lay follower who has gone for refuge for life.”