Have you thought much about how to update it for 2.0? I am looking at my (edited) copy and wondering where to begin, and how to measure the difficulty of handling a planet where the hydrosphere freezes for half of the year.
Honestly, I don't plan to ever play with eccentric orbits.
But if I did, let me think, what would I need to do with this.
I guess I'd never really be interested in the current CC. I just care about the max and min.
Well, unless this planet has a very long orbital period.
In which case I might care a lot about the next, say, ten years. I still need to know what happens in the decades after that, but timing really matters.
However, the timing issue might not matter all that much in practice, because nearly all reasonably terraformable planets have reasonably short orbits (no more than a few years).
The ones that are reasonably terraformable and have very long orbits are probably orbiting an immense star, which is going to make the distances involved so large that I'd probably never consider colonizing it anyway.
So, assume I just ignore timing, because the orbit is far shorter than a typical terraforming timeline.
I would need to duplicate every existing column that refers to surface temperature, and calculate once for max distance and once for min distance.
Actually, might be simpler...I haven't looked at the formula that calculates base temperature from the orbital properties, but orbital distance is surely a factor. Probably an inverse square relationship?
Whatever it is, calculate the base temperature at min distance, and use that plus the eccentricity to infer the temperature at max distance.
Now I just need my "how much do I need to cool the place off" columns to consider the temperature at min distance, and my "how much do I need to heat the place up" columns to consider the temperature at max distance.
In nearly all cases, I'd expect only one set of columns to produce a positive number. Meaning I only need to either heat the place up or cool the place down, and I just need to make sure that I don't do so much of one or the other that I make things worse on the other side of the orbit.
If that's the case, or if both columns show a positive number, then there is no way to get this place to CC 0 permanently.
So, figure out what needs to be done so that the min and max CCs (for temperature) match, and that's my target CC.
In fact, the logic might be simpler overall if you just start from here.
What's the min and max temp CC right now, and how much can I reduce the higher one before the two are equal (or until I've changed the temp as much as it is possible to change it)?
In ideal cases, you can get them both to 0.
I don't even want to think about the hydrosphere issue.
My hunch is that only a vanishingly small number of otherwise desirable targets will be crossing the freezing threshold post-terraforming. Although I'm assuming roughly Human temperature ranges. Certainly one could play a race that likes colder places.
Maybe just figure out, based on orbital properties, how much hydro will freeze per orbit, and add enough extra hydro so that the hydro CC won't exceed the target CC.