Thanks for the replies everyone

To answer the burning question,
I used debug, just not for building any buildings. I've only got 500 hours in the game, but I have all the achievements except Established and Tenure, and I too am confident that I can start a game on harsh+hard and survive just fine.
More specifically, terraforming isn't something I couldn't-not debug. The risk of getting a tile wrong or misshaping an island was too great for me, so I debugged that instead of saving, terraforming, and reloading if something went wrong. I also debugged some of the decorations so that I could play around with aesthetics, but a lot of the decorations I used were ghosted or just free, which is always appreciated. And now that I'm remembering it, I debugged a chunk of those castle walls. They look pretty simple looking at them built, but the wall segments, tower segments, and corner segments are all different dimensions and I made a mess trying to join them perfectly a few times.
I don't mind using debug, but I still like creating and balancing an economy, so I tend to play the game as-intended just so it's more fun. It also ends up dictating how much of what I need, which gives me reasons to build areas a certain way, which leads to unexpected areas to madly fill with an insane amount of decorations. I completely agree: "There's never enough deco stuff!!!"