I'm pretty sure they will eventually find a way around this. Whether it be a separate API or forge. I don't see this being the best way to deal with things!
It is nice that you can test modifications to JSON files like that, I can see that being extremely handy for myself as well.
I myself would nerf the vanilla swords. They are extremely overpowered as is if you really think about it. I don't see many other effective ways of increasing the incentive to want the new swords besides the "cool" factor.