Nice job. I lived in Taiwan for years and at the time couldn't read simplified very well, so I used a relatively popular browser extension called 新同文堂 which did something similar.

https://github.com/tongwentang/tongwentang-extension

Hey folks, I made a super niche Mac app called HanToggle. Select Chinese text in most apps, press one hotkey, and it switches between Simplified and Traditional in place. Press it again to switch back. Free, MIT licensed, and fully local. No account or tracking.