Yep, we definitely could have explained the scoring better! The way it works is each subchain is calculated separately, then added together (that's what the big green/red scores are). So if you had 3 bombs in a line and detonated the middle one, you'd create 2 subchains which would be summed together as: (middle bomb + left bomb) + (middle bomb + right bomb).
Anyway, thanks for taking the time to try it!