[Grammar] ... an experience that had actually happened to Stevenson's father ...

[kadioguy]

[In the novel Treasure Island, originally by R. Louis Stevenson, retold by Rjhon Escott, from Oxford Bookworms Library]

ABOUT THE AUTHOR

Robert Louis Stevenson was born in Edinburgh, in Scotland, in 1850. His father was an engineer, and in 1867 Robert went to Edinburgh University to study engineering himself. He found that engineering did not interest him and trained to be a lawyer instead, but in fact he had already decided to be writer.

[...]

Stevenson began to write Treasure Island to amuse Fanny's young son, Lloyd, during a rainy holiday in Scotland, and he read it aloud to his family each evening. The story of Jim hearing about the mutiny while inside an apple barrel was an experience that had actually happened to
Stevenson's father when he himself was a boy.

[...]
----
1. Why is the blue text used? I know that's for emphasis, but I can't see a reason for that.

2. Why is the red text in the past perfect? What does that mean? A farther past?

How about just the past simple? I.e., ... was an experience that actually happened to Stevenson's father when he himself was a boy.

 

[GoesStation]

1. Why is the blue text used? I know [STRIKE]that's[/STRIKE] it's for emphasis, but I can't see a reason for it.

2. Why is the red text in the past perfect? What does that mean? A farther past?

1. It emphasizes that Stevenson was following in his father's footsteps.

2. The past perfect makes it clear that the experience happened further in the past than the writing about it. Many Americans would use the past simple nowadays. I'd stick with the past perfect.

 

[slevlife]

His father was an engineer, and in 1867 Robert went to Edinburgh University to study engineering himself.

"Himself" is not used for generic emphasis here. It is used to emphasize the similarity with his father. You could replace the word "himself" with "like his father" for the same effect. If you just removed the word though, the sentence would sound stilted -- in other words it would be too focused on the facts rather than telling a story and connecting the pieces together.

The story of Jim hearing about the mutiny while inside an apple barrel was an experience that had actually happened to Stevenson's father when he himself was a boy.

The use of "actually" here has a similar effect as my last explanation. It is emphasizing the connection of his father's experience to something Stevenson wrote in his book Treasure Island. The use of "had happened" rather than just "happened" is emphasizing that Stevenson's father had the experience before Stevenson wrote about a similar experience in his book. So it's further in the past than the reference point of Stevenson beginning to write his book.

Edit: GoesStation beat me to it!