I need clarification to:
1. Artillery reaction fire. Can artillery reaction fire on any unit that fires within it's maximum range (9.1.2 first bullet) or just on enemy artillery unit that fires within it's max range (and that's why that "counter-battery" phrase is in brackets)?
Also see 9.4.2, It may react to being fired upon outside its grazing fire range, and since artillery is the only thing with a range greater tha 1, it is assumed that you would be reacting to artillery fire. It does NOT react to any fire, just fired directed at the artillery unit.
2. Stnregth ratio. Rules say (that little table in 11.3.4) that modifiers are tied to ratios in ranges. "1:2 or less", "1:4 or less", etc. So if the strength ratio is 2:5 we drop factors in favor of defender to make a 1:3 which still give us -1 modifier. Or -2 and rules should say that we drop factors down to the nearest strength ratio in favor of defender.
Yes there are two tiers above and below, so in the example 2:5 is simplified to 1:3 is still greater than 1:4 so only 1:2 -1 applies.
As often happens, you have 3 attacking 4 strength which rounds in favor of the defender to 1:2 and a -1 applies. The 4 attacking the 3 has no modifier as it rounds in favor of the defender to 1:1