1. Most likely, the angels will form stacks equal in number to the number of archer stacks.
2. The strength of an army is most conveniently calculated by simply multiplying the number of units in a stack by the "value" figure. For example, 12 archers is 12*184=2208.
3. The strength of the angel army should definitely be calculated based on 6+3, since the strength of improved level 7 creatures increases by a factor of 1.5 to 2 compared to unimproved ones (taking into account special abilities, such as shooting/resurrection, etc.), or simply by "value": 9*5019=45171; 6*5019+3*8776=56442.
The PhysMig wasn't designed for a quick 15-minute calculation, and if there is a formula or dependency provided, it works; you just need to understand what initial data to use in it.
And regarding the strength of the angel army, the trick is this: Invisible counted 195 units across three stacks.
So, the maximum number of archers in three stacks is 195*1.5=293.
Then, with 294 archers, there would be two stacks, right?
It seems so... But no: with two stacks of archers, there are already 4, not 3
It turns out to be a rather gloomy and complex calculation, but it is definitely useful...