Does the mod change the net total number of rare items, if it doesn't have to? E.g. in a sector with one of everything except a plasma dynamo and two hypershunt taps, will it only add a plasma dynamo somewhere or will it replace a hypershunt tap to "conserve" the number of rare items?
Guessing it only adds because I've been getting richer hauls of colony items with it on, and it's pretty normal for me to be missing 1-5 types of items.
Also, would it be possible to add a setting for number of rare items to guarantee? Like I don't need any nanforges or synchrotron cores since those are raidable, it's really just catalytic cores and hypershunt taps that kind of determine whether a huge endgame reward works at all....
Yeah this mod only adds, so technically the sector will be slightly more powerful than vanilla. Vanilla doesn't actually store the values of the loot in salvage, it only stores the seed, so it would've required the mod to evaluate every single piece of salvage during sector generation, which would have added a lot more complexity than it was worth. I figure that most players don't actually salvage the entire sector anyway, so the experience should be the same for the most part. IMO it's still balanced because finding that last item is still just as hard, except that you now know that eventually you can find it if you strip mine the entire sector. I had a campaign where even with this mod I never found a pristine nanoforge, so I did the usual and raided Chicomoztoc

When I finished the campaign, I checked the save file, and discovered that the guaranteed nanoforge was located in a star system I already salvaged, it was just out in the middle of nowhere...
Sometimes, when loot generates more rare items than I expected, I actually check if it was from this mod. The vast majority of the time, it was actually just Vanilla RNG rolling in my favor.
If you want to remove nanoforges and synchrotron cores to incentivize raiding, you can edit modSettings.json and remove their respective lines from the rare_items array. You could also remove everything except the catalytic core and hypershunt tap (id is "coronal_portal"), if you want.