HI @Lee
(don’t know if this is important to read if you have other things to do…)
I would like to explain the parts that I (think I) understood and point out the corrections I would have done, to the powerpoint you presented in the PM of 15/04.
I am not claiming i fully understand things but maybe if we put our brains together we might get there 
The comparison the architects did is for me a comparison between their simulation file and a more detailed price calculation based on estimates. I have the impression you want to compare things that happened on different moments? My interpretation: they compare things with same inputs, same moment in time, but different calculation methods.
I would have renamed the right column ‘calculation based on estimates’. For me both figures delivered are linked to the avant projet.
The last simulation we received came to a total price of 4461 euro/m2. We received this - if i remember well- after the reduction of the Oaktree units with the covered entrances.
What I am pretty sure they did: they update this simulation file again, now applying the correct m2 of terraces, the correct m2 of surface in the -1 of Obelix. This leads to a new total price of 4467 euro/m2.
So for me this price should have gone under the column ‘FS’
Ps: this new simulation lacks - according to me - still some updates (m2 vendables,…)
In this file from the architects, just above the ‘Options’ section, you see they take the amount from this simulation file and make the difference of the detailed price calculation based on estimates.
The open question is than: what figures fits on the ‘total price’ row of the right column => this we don’t have as the detailed price calculation based on estimates only focussed on casco.
The casco price of 3491 euro/m2 : I guess it belongs in the left column, as I assume they didn’t have time (yet) to calculate a casco price (which includes vat, fees,…) based on the estimates, but that i am not sure off.
The building row: for me this data should be the same in both columns. We are comparing different systems of calclations (according to me), not calculations with different inputs.
The ‘not included’ row: same remark as above: both columns should ‘not include’ the same things.
In the right column you mention the finishings of the commons and private units are not included. You have a point. The detailed price calculation based on estimates is purely focussed on the casco. But it is confusing that you mention a total price (first row), because that total price is a price including finishing of commons and units.
For me the workshop is included in both cases.
(so coming back to what i replied to ‘how come the casco price goes down in the right column while the total cost raises’: the answer is ‘I don’t know’, because for me in both left and right column the same amount of m2 vendable should have been taken into account. So big inclarity for me is: is the 3500 euro/m2 casco linked to the FS and the 3494 euro/m2 casco???)
(hope i created some clarification, and not the opposite)