Nice job! There have been quite a few of these language substitution extensions over the years. (Language Immersion, Polyglot, MindTheWord, etc.) I have a personal extension that I wrote (close to 12 years ago at this point) which does the same thing - translates random words on websites as you browse according to your linguistic level. It vastly predates LLMs though so it's all built on sentence segmentation, POS an…
LLM's makes this kind of words substitution more easier and accurate. we have also tried some methods like NLP, but effect is mediocre, but if we want use it in specific scenarios, NLP maybe more efficient.
The website's visual design definitely needs improvement. we are currently work on it.