RE not having hearts by using the web version, the Japanese course is lacking furigana on the website, which is a bit of a hinderance. Since they introduced the ‘awesome’ new voices and broke a bunch of the readings, it’s even harder to without the furigana as a lot of the readings are wrong. The furigana is about 95% correct, so at least you can see what character you are looking for, when none of them make the correct sound. Obviously you want to read the kanji first and actually learn, but you don’t want the lessons to be made unnecessarily difficult by complicated characters and incorrect readings. Skills like Law, Politics, Science and Resources are very complicated-kanji heavy. The website version is very difficult for these lessons (but hey you can keep trying until you get it right).
I use the website to get through the annoying skills that have very few accepted answers, as it’s too hard on the app when you are typing answers that you know are correct but they are not on the list.