You know, it might not even be that Andrew remembers much about writing Act 5; it could be that rereading Mindfang’s journal is just doing a really good job at jogging his memory as to what Alternia was about. It’s sort of a masterstroke of worldbuilding, and I think Andrew himself describes this quite well in a part of that Book 6 page 309 quote that I left out of the article:

[…] this isn’t a rabbit getting pulled out of a hat, it’s an answer to some questions that were implicitly being asked by the story, and the answer was already kind of boxed in by a lot of pre-established lore. This is pretty much how worldbuilding in general works. You build a world, then the world keeps seeming to ask these implicit questions, and many of the answers are shaped and confined by the facts already spread out on the table. This process leads to results which are: interesting! Arguably more interesting than if you just pulled some ideas like this out of thin air. These ideas arose naturally and logically from a continuously emergent framework, which makes it all feel more sturdy, and perhaps explains why this facet of the story was very successful in capturing people’s imaginations.

All the “new” things we learn from Mindfang’s stories are really things that we should have already been able to guess based on the things we already knew - which is exactly why all of this commentary just has me going “well duh, I figured that out all on my own!” Telling a second parallel story about a second parallel set of trolls was just a way of sealing with glue the cracks between the foundations already laid by the first story about the first set of trolls. No wonder it was so successful in capturing people’s imaginations indeed!

This idea that a world should be architected by shining a mirror back on the parts that have already been built has always been one of my strongest philosophies, and I think it’s something that Homestuck, a story whose second language is patterns and repetition, excels at. I think having this put into words goes a little bit of the way toward explaining some of what felt like Hiveswap’s shortcomings to me: even though originality is always a virtue in telling a new story, sometimes a sequel that does a poor job of synergising with its predecessor is even more egregious than a sequel that contradicts its predecessor outright.

You need to strike a balance between building windows into new avenues of storytelling and placing more bricks on the wall you’ve already established, or you run the risk of building a greenhouse instead of a cottage.