Now, I see a couple of possible issues.
Firstly, I think you didn't take corruption properly into account during the growth turns. Looking at the 4-turn cycle in Dunderhead, turns 62-65, you have 8 uncorrupted shields on the second turn of the cycle. But one of those shields that get added with growth goes to waste, so in reality I think we'll only produce 7 uncorrupted shields that turn. That would be a kind of a problem, because it would put the whole cycle at 6+7+7+9=29 shields. So it would seem that we need sizes 5 and 6 for the 4-turner in Dunderhead.
There's a similar issue with the 2-turn cycle in Ignoramus. On the second turn of the cycle one of the 2 extra shields would again go to waste, leaving the cycle at 4+5=9 shields. However, this we can simply fix by mining another bg, so that it'll be 5+6.
Then, it appears you've dropped 2 people out of Ignoramus when rushing, but at 42 shields it only costs 1 citizen. Also I'm not sure if I'm reading the chart correctly, but I think you're dropping Dunderhead's population on the chart a turn too late. We'd have only 2 citizens on turn 45, right?
Finally, there's the issue of happiness. How high do we need to have lux tax at to keep Dunderhead's people content? I'm afraid it's going to be so high that just because of that we can't afford to rush with more than 1 citizen at most. Note that it wouldn't necessarily have to be in the end. We could switch to settler at 10 shields, rush it with 1 citizen and switch back to granary. Or the same thing at 20 shields, except use barracks instead of settler.
Just one more thing.

I tried to guesstimate what would happen in Dunderhead if we didn't rush the granary at all. The granary would surely complete around the same time as the first settler after the rush, and then we'd be ready for the 4-turn cycle right away instead of doing a couple of 5-turn settlers. So in practice rushing with 2 people only seems to save a couple of turns at most, with the cost of some extra unhappiness for a significant amount of time.
I'm afraid this became a little messy, hopefully you can make some sense out of it.
