I've just finished Cerys, so I thought I'd post my thoughts.

I spent a lot of time fumbling around, trying to work out how to even make progress. Trying to remember what recycled into what, how to get each resource, hand-feeding things into recyclers, etc. Fulgora's recycling mechanic, added to blocking external supplies, locking out logi bots until fairly late, the freezing mechanics, unmovable heating towers, etc made Cerys significantly more difficult than I remember Fulgora being.

I felt like getting to the point where I could power the reactor consistently was too hard. I got there in the end and built a much larger base, but I nearly just left once I'd limped along far enough to get the science I needed.

A few things on Cerys are intended to be mysteries especially early on, but I think there's a couple of things that aren't supposed to be but just aren't well explained. It was only by complete chance that I spotted the gamma radiation entity in Factoriopedia - I had just resigned myself to constantly taking damage and stacking personal shields hours earlier. Being able to use concrete in shallow water was another - I found that out after I was almost done with Cerys by reading the changelog. I don't know how you'd discover that except by accident. Super force build doesn't place concrete like it does landfill or ice platform.

I feel like mineral leaching is intended to be a good source of iron, but it drinks so much sulfuric acid that I mostly wound up crushing asteroid chunks instead.

Anyway, just my experience with Cerys.

It's indeed trickier than standalone Fulgora to get to grips with each new system. On the specific points you raise: The reactor gameplay is tuned to need the development of a working plutonium farm (we may look into rebalancing at a later date but only when certain of the breaking changes and there many underappreciated issues here); In v4.18.7, a note about radiation shielding has been added to the reactor entity description and the bug with ghost-placing buildings on Cerys water has been fixed; mineral leaching creates significantly more iron than is consumed to make sulfuric acid and is indeed the primary source of iron, but this ratio can be further increased by including productivity modules in the loop.

Thanks for sharing.

My issue with mineral leaching wasn't the iron, but the amount of sulfur. Running pipes, solid fuel and methane ice to distant Fulgoran cryogenics plants for methane ice dissociation is much more work than just slapping down some gun turrets and feeding metallic chunks into a crusher.

Sure, sulfur/light oil is the other constraint. This is the part of the game where you expand your cryoplants. Your other option is to improve the modules in your existing cryoplants.