Scientology seeks to exploit the "abreactive" process. (Unearthing previously buried trauma with subsequent relief.)
A suffering soul is helped by a cult leader and becomes his slave.
The term engram predates Dianetics. Hubbard P-T.-Barnumized it and cultified it.
In his 1923 book, 'The Mneme', Richard Semon used the term engram, which he considered to be a "
stimulus impression" that could be reactivated by the recurrence of "
the energetic conditions that ruled at the generation of the engram."
The author of
Science and Sanity, Alfred Korzybski. used the term "hurts," and wrote in 1935:
"...
We begin to check this... process of piling up 'hurts' on 'hurts'... new 'hurts', in practice, are usually related or similar to the old ones; they would revive the older 'hurts'. Accordingly, he [the person undergoing abreaction would]
not only 'live through' the older experiences but at once revive them, and after re-evaluation, eliminate the harmful effects."
The chapter 'Origins of Dianetics' in the book 'L. Ron Hubbard, Messiah or Madman? contains more info.
The information you have is mostly Dianetics circa 1950, with prenatals, sperm dreams, Attempted Abortion engrams, etc.
There no doubt are such things as "hurts" and such things as traumatic experiences. Hubbard extrapolated from this and while he, IMO, did have some innovative moments, he also had a self-serving hidden agenda, an agenda that affected Dianetics and Scientology since their earliest beginnings.
If you're considering entering the wonderful wacky world of Scientology, strongly recommend first reading this short article:
Ex Scientologist - The Scientological Onion