So I'm running Rampant Fixed, and I'm not sure if Rampant is doing it, it's a feature of Carna, or a combination of both, but Carna's robots are randomly spawning on Nauvis in the middle of my base, and when they do it's equivalent to an Atomic Bomb going off around them. It destroys everything, included entity ghosts.

Is this normal Carna behavior, or is Rampant doing very bad things? I have yet to get into space and every time this happens I lose about an hour to rebuilding everything broken.

I'm going to need more details. Are you running other mods, how long into the game are things like this happening, is it happening after a triggered event? To my knowledge, Rampant Fixed shouldn't be running any codes that spawn enemies anywhere and Carna's enemies shouldn't affect other surfaces. There are no control scripts that spawn or direct Carna's enemies either.

The only mods modifying enemy behavior is Rampant: Fixed, tho there are a couple mods that add biters, Armored Biters, Frost Biters, and Arachnids. They first showed up about 10 hours into the save, evolution at 62%. I had yet to even unlock the science necessary to unlock the rocket silo (Rampant means lots of time fixing and preparing defenses), let alone the research chain to unlock Carna. I only noticed the spawn because it spawned directly on top of my steam engine stack and killed power base wide. It ignored the 4 layer deep wall that surrounds the base, the base itself is on an island (which I gave a 2 chunk buffer between the water and my walls, otherwise Rampant's ocean migrations will just spawn inside the walls.) All other spawns handled by rampant cannot spawn within 2 chunks of a player placed entity, yet the Carna enemies don't care and will just drop anywhere there is something densely packed. I figured out if I put a thick enough wall barrier (now 8 layers), it'll prefer spawning on top of the wall cluster instead of deep in my base, but it still explodes on arrival and removes a pretty massive chunk of my defenses. It was manageable until the first time I finally left Nauvis and it spawned while I was on Mulana before I had built a rocket for a return trip. I had to revert to a save 3 hours before because it was unrecoverable. I've since added Teleporters rather than remove the mod to mitigate it some, but I still have no idea WHY it's happening. There are no mod options related to it in either mod, nothing in your code appears to spawn stuff on surfaces other than Nauvis (but I admit I'm not really good to reading lua), and nothing in the surface of rampant seems to spawn enemies from other mods with impunity. I decided to ask here first since of the planets I have installed that have custom enemies, Carna is the only one stuffing enemies on Nauvis.

Carna doesn't have any code that spawns enemies in its control scripts. Given you have Mulana and a number of other mods installed other than Rampant and Carna, there is likely some sort of interaction going on with another mod entirely. Without 100% of the information, it is unlikely whatever is causing this can be fixed, but I am unsure it is something from Carna mod itself.

There are no control scripts that spawn enemies, and the Carna objects + bases are the only entities that will spawn in new enemies and those only can spawn on Carna world. You could probably upload your save file and I can double check and see for myself what's going on, but at this point I am skeptical that Carna mod has any real involvement in your impending doom.