If those two lines remove 100 of complaints per day but add 10, it's still a net positive change that creates value. Especially since special requests were never supposed to be a guarantee in the first place.
The fact that one type of complaints get converted into another type is an unforeseen consequence. But shipping the change is still worthwhile because it's the only way to expand your domain knowledge and learn about those consequences.
And then they released the product in Japan and got complaints that there were a whole lot of special requests that were being ignored (because you can encode far more information in those two characters)
Maybe you do need a software engineer after all?