Dear Lords
it all depends at with part of the production is applied the reduction
i mean, when u calculate the production according with the items or boost u have or apply, some of them is made from basic production and some of them is made with the sum of all buildings production.
for example u have a farm that produce 500 food per hour x 6 farms = 3000 food per hour + the keep that produces 191 so your total base production is 3191 per hour
to this base production you have to calculate and add your buildings i mean take the life springs and apply the % over that amount
take also the house of unity and same . Once you have this two amounts you have to add both of them and sum to basic production.
from this point with the new amount you get, you have to calculate every boost percentaje, resource boost, parangon status, lost art boost, hero boost, ..... and sum all them to the total and this makes the total number production you see
now we have to wonder in what amount is the reduction boost or % applied...in basic production or in total production, after or before applying builds boost or item boost ??? ... for me that is still the unknown part
hope this can help you all to clarify your numbers
Regards