Yeah, a lot of the Space Age features aren't too well documented yet. I have had a better time just looking around in the code for examples: space-age/prototypes/recipe.lua has some good examples. They usually restrict recipes by atmospheric pressure: Aquilo has pressure of 300, Fulgora has 800, Nauvis has 1000, Gleba has 2000, and Vulcanus has 4000. However, you can also play with gravity and magnetic field. This is all defined in space-age/prototypes/planet/planet.lua if you want to dig deeper into it.
For what it's worth, automating stuff and procedural generation is fun, and it's always satisfying when stuff "just works," but, if you ask me, I feel like a certain amount of hand-coding in order to create a good mod experience is probably always going to be necessary. For example, you couldn't find holmium ore as a resource because it just isn't one; it solely exists as an item, created as a random result from scrap. So procedural generation focused on resources would miss it entirely.
Anyway, I hope this helps a little!