Ormand is working on fixing or at least finding out what the issue is. It should not be supplies in stock ATG (A New Dawn), since the AI is actually programmed there to get the correct amount of supplies made. I have suggested that the issue may be one of the AI transferring too many times between units, but this is only speculation.
There is no easy way to control what the AI has in it's formations. It does not use the TO&E, so that is not a solution.
Perhaps one could define a large number of standard units (Rifle Division for instance, Tank Division etc.) and specify the exact contents as a predefined unit. If these units are then bought by card, and the AI is not allowed to transfer between units (there is a rule var), then I guess you could have a form of AI that uses units. This would also require that all locations either produce PPs or Supplies. (Since there would be no way the AI could make use of the units it makes).
This would require making a massive amount of units, since there doesn't exist a TO&E template for PreDefined units. So if you research Rifle II, you would now be able to produce the Infantry II type PreDefined Unit. Of course, if you don't have MGs and Mortars and Bazookas upgrade at the same time and they are components of the predefined unit, you would need more PreDefined units. So to make things simpler you might want to consider making a modified research tree that only included, say Infantry II as a catch all for Rifle II, SMG II, MG II, Mortar II, Bazooka II. Of course it should be more expensive.
So now that we got those PreDefined Units set up... and believe me, you will need many... you then calculate what they are worth PP wise, and set the card cost at that. Unless you of course want to make this way of doing things AI only, in which case you can do away with cards, since the AI doesn't use them. You would need event code instead (or rather any AI would need code). The code here is when should it produce what. Now that can be done, you just set a ratio up or something like that, defining when the AI should focus on one PreDefined Unit or another. You can also find out what researches it knows, so you can guide it along. Then for the next unit, the process starts over, until you get all the PPs you want it to use, used. Of course you have to decide where these units "pop up", but that is rather minor, it could be at the capitol for instance.
A side effect of this approach is that each unit will fight until it is ground down. So you will have very small units at some point, that the AI really won't know how to handle logically. Still it is a solution...
Be prepared to do a lot of testing though. The right unit size will be crucial. Any miscalculation on that, and the AI won't be worth anything, ...