We launched a project to help language learners learn vocabulary effortlessly last year.
You can mark and save the words you don't understand, the saved words will be marked automatically if it appears on subsequent web pages, thus you can review these words in different context and repeat, repeat and repeat. One year later, the reading becomes easier. For example, English learners can mark words on twitter while they surfing the twitter.
Vocabulary calendar, Vocabulary flashcards, Sentenct snapshot, etc.
I think you've made a great leap by releasing this product, but there are some issues that might sabotage your efforts.
The pricing page on your site is full of broken English. You've put a lot of effort into coming up with a viable business plan, and promoting your product, but it would be important to apply some finishing touches and ask a friend to proofread the site.
The extension's code is obfuscated, which is against Chrome Web Store policies. Minification is allowed, if you're looking for ways to save space. Reviewers take down obfuscated extensions once they're discovered, and they also remotely disable existing installations, so this would be important to quickly address in an update.