As it says the bone echo is increased by 5% for every 30% CSD you have.
I have a total of 558.5% CSD so divide that by 30% you get 18.6, so 18.6 x 5% is 93%
So why is it only showing 60% bonus?
The value you see on the stats page is the crit strike damage after multipliers. Scroll over it to see the value “from items and paragon”. Use that value to calculate the multiplier.