Ahwaric
Shrubbery-hugger
Great post Kalina, thanks a lot! 
A couple thngs before I start adjusting yields according to it
In general, people say the guilds are overpowered. Yet, your calculations show that yields are more or less the same as in BtS (I tried to keep close to these values when adding guilds).
So, I think the reason is the lack of competence and thus, possibility of creating supercities with multiple headquaters, gaining bonuses from more cities than in BtS
Edit: three more things: Weavers have special building, the clothhall (requires several markets)
The bonuses to commerce & yields scale with map size. Kalina, I hope you have used the same for your tests with BtS & Orbis
and finally, maintenance.
For guilds, it is just 25% of the BtS value, so probably should be increased. I think doubled... (will be 50% of BtS), or tripled (75%). Standard BtS value is too much even for BtS (you loose money because the guild works good)
Another problem are buildings reducing maintenance (civics are already nerfed for 0.30). I think these should apply to guilds, but might need some nerfing. Especially for the order - it is just too easy to make no maintenance city, and that is a problem not only regarding the guilds...
In short, my current proposals:
to consider: nerfing maintenance reducing buildings & civics

A couple thngs before I start adjusting yields according to it
In general, people say the guilds are overpowered. Yet, your calculations show that yields are more or less the same as in BtS (I tried to keep close to these values when adding guilds).
So, I think the reason is the lack of competence and thus, possibility of creating supercities with multiple headquaters, gaining bonuses from more cities than in BtS
- I do not want to introduce competition (above I have explained why), so I can disable multiple headquaters in one city, or further lower headquaters commerce. It is already 25-50% lower than in BtS. I can make it 1/2 or 1/3 of the current value.
- Also, should I keep the yields at BtS level, when there are guild specials (units, spells, buildings) non-existant in BtS? Especially that you can have 7 standard guilds in one city (CoE & CoT do compete, GotN is not a standard guild).
- Seems that discovering resources will have to go after all...
Edit: three more things: Weavers have special building, the clothhall (requires several markets)
The bonuses to commerce & yields scale with map size. Kalina, I hope you have used the same for your tests with BtS & Orbis
and finally, maintenance.
For guilds, it is just 25% of the BtS value, so probably should be increased. I think doubled... (will be 50% of BtS), or tripled (75%). Standard BtS value is too much even for BtS (you loose money because the guild works good)
Another problem are buildings reducing maintenance (civics are already nerfed for 0.30). I think these should apply to guilds, but might need some nerfing. Especially for the order - it is just too easy to make no maintenance city, and that is a problem not only regarding the guilds...
In short, my current proposals:
- headquaters commerce cut to 1/3
- slightly lowered yields per resource
- a bit more maintenance (35-50 % of BtS value, instead of current 25%)
- removed resource discovering spells
- nerfed guild maintenence discounts on civics
to consider: nerfing maintenance reducing buildings & civics