I’m so sorry for your loss. I know exactly what you mean. Going over the same words your mom did and holding the same copy she did does feel like a valuable connection. I did the same when my dad passed.
Onto House of Leaves. I really liked it, but the narrative structure is very bizarre. The story in the text versus the story in the footnotes can make it harder to follow. You do need to read everything, including the appendices, but not everything is important. There are a lot of superfluous details about the architecture and the point is basically just that the interior doesn’t match the exterior. So, read everything but you don’t need to worry about memorize every detail. I know this is personal preference, but I read the footnotes in larger chunks when they continued on for multiple pages. Normally, most people read the main text, stop at a footnote, and read that whole footnote, then go back to the text. But for HoL a lot of people stop at the end of the page. I think stopping at the end of the page cuts off the story and makes the book harder to follow BUT Danielewski did it intentionally because he wanted people to read the book in a slightly different order every time making the book its own House of Leaves.
I specifically don’t use Goodreads because you HAVE to give a book a certain number of stars to record it as read. If I look back at books I’ve read I only care about how much I enjoyed them. I don’t want to give 1 or 2 stars to a book I personally didn’t like, but thought was well-written and well-executed if other people can see it or use it as a reference point. But, I think it’s that Goodreads stars are mostly used as a personal reference by readers of past books. Popular books are often poorly written (Twilight, 50 Shades of Gray, Colleen Hoover, etc). Having books without happy endings is likely an important factor in how popular it is. It doesn’t mean the book isn’t good.