Any way to mod/change Independent Strength for a Scenario?

[Tenryu]

If you mean the non AI player indies, you can set the "#Poptype" in the "blahblah.map" text file to get the basic type of indie you want in a provence then use the "independent strenght" setting when you choose a game to make all indies stronger or weaker as you might wish.

I haven't tried adding multiple poptypes to a provence, but it might work, if it does then you have close to what you want I think, albeit maybe not everything.

Again the "#commander " and "#comname" might work for some of your purposes.

cheers