Terraforming's not convoluted. It's literally get tech, get energy, click on planet inside your borders, click terraform.
Get Tech, get accompanying tech, get terraforming resource, get the other terraforming resource, put up terraforming platform, start terraforming, wait a very long time with heavy drain.
Versus
Get tech, build it.
Terraforming is literally get tech, click button. The resources just reduce the cost. There is no 'heavy drain'. The whole cost is up front.
If you need to change the world's hydration category, you need Terrestrial Sculpting. If you need to change the temperature, you need Atmospheric Manipulation. If you have both of those techs you can change any normally habitable planet to any other. For tomb worlds you also need Climate Restoration. If you want to make a planet into a Gaia, you need Gaia Creation.
Normal terraforming costs 2000 or 5000 energy and either 5 or 10 years, depending on the target climate and what you're starting with. Each resource you have access to (terraforming gasses/liquids) gives a 25% cost discount, so you can halve those costs if you have both available. You will probably NEED that discount for gaia world terraforming as that costs 10,000 energy without the discount and something like 40 years.
Terraforming is a mid-game tech for any normal application, with late game techs for gaia/tomb worlds. The main cost is time, as the energy costs aren't all that ruinous for a mid-game economy and can be heavily discounted. It's still a simple process.
Building a megastructure requires you to unlock the appropriate ascension perk, which requires you to finish a tradition, then you must build several sequential construction projects which each cost an assload of minerals. Ringworlds must be built in stages, finishing each section requiring 2 or 3 (i forget) projects. Dyson spheres are also 3-4 stages. It isn't all that complicated either, but much moreso than researching Terrestrial Sculpting and clicking terraform. The only simple one is habitats, and everyone gets those. They're just big space stations.