The Lunar factory is not a part of the set buildings but a stand alone one.
There for it is a shame if you get it in the orc or woodelves you mis on the resources they could provide.
But as a mana source in the higher chapters it is a very nice one
{edit}
Looking at the set buildings again but now adding the numbers I start getting my doubts.
At chapter 19 you get a total of:
1300+650+1300+1300 orcs 4550
900+405+765+1125 seeds 3195
2600+3380+3900 platinum 9880
1760+2640+3080 tree sap 7480
880+1408+1760 moon stone 4048
So if you are a platinum maker you get the maximum of your bonus goods, a little less on the tree sap and way less on the moon stone.
In this case you should get 9880 on your T4+2, 7480 on your T4+1 and 4048 on your T4.
That way it should have the same value for all players, no matter what their bonus good would be.