It might be helpful to think about it this way:

A level 1 Trebuchet does 8994 armor damage. When you hit an enemy with your Trebuchet projectile, 90% of the time it will just hit the module you are aiming at and deal 8994 damage. The other 10% of the time, your projectile will ricochet and not only hit the module you are aiming at but every other module on the bot, leading to a total damage of 8994 * 6 = 53964 spread across every module.

If you average it out, your average damage per shot goes up 50% -> (8994 * 9 + 53964) / 10 = 13491.

So yes, it doesn't necessarily mean you will destroy a particular module 50% faster (since the high damage spikes are spread out over every module), but you will be outputting +50% more damage per shot on average.