In the bouncy wavy notation is an error in the example script. If you want change the hight/amplitude of the boncy wavy tag, you need to use "a" instead of "h". For example: "{bt=a10-s0.5-p10.0}" instead of "{bt=h10-s0.5-p10.0}"
If you just looked into the script of the example VN, you might have noticed that the amplitude does not change. Since the boncy wavy tag is the one I plan on using in my VN, I looked into it more closely. The example says "{bt=h10-s0.5-p10.0}" but it should be "{bt=a10-s0.5-p10.0}" since the code takes "a" as argument for hight/amplitude.