1. I've tested 元気 and it's furigana is correct 「げんき」, I guess the described problem occured because you used in Duolingo, which may frequently split a single vocabulary into multiple HTML elements, and this addon process the HTML elements one-by-one. This is a technical limit. 2. Such wrong furigana are maybe sometimes due to the used dictionary or igo.js, which is prepared by another software project, so it's not what I can fix. You can see the GitHub issue for detailed info for this. 3. You should use this addon for reference only, it's impossible to provide 100% correct furigana for kanji. This is technical limit, even Google's or Apple's AI can never do this 100% correctly. You should use an independent dictionary addon or app to ensure the vocabulary you want to know when in doubt.