All you wanted to suggest

When I am watching the definition of a word, I often see another word in the definition which meaning I don't know, so I press to see this new word, and when I see it what it means, I want to return to the previous word that I watched, with a Back Button.

Currently when you add more options to the Playback Sequence of Narration, it extends the list out horizontally and you have to scroll left/right to see all the options. I suggest this list be stacked vertically so as to see all the currently-selected options more easily at a glance. Also, it would be nice if you could select a different text-to-speech voice for each Paragraph/Translation option. I use the default Google text-to-speech options on my phone/tablet, but there are often multiple voices available for each language and it would be nice to be able to hear more than one when using multiple "Paragraph" selections in the Playback Sequence of the Narration. (For example, it plays the French paragraph once with a male Parisian accent, then the English translation, then the French paragraph again but with a female Quebecois accent)

ONLY FOR SUBSCRIPTION OWNERS. The ability to switch to another application and a pronunciation does not stop. At the same time, a media player will appear in the notifications panel, in which it will be possible to do A pause A rewinding Return to the application to the place of a pronunciation Repeat a pronunciation

Bold, Italic and other font appearances

there are many books where a lot of information is hidden in footnotes

It might be implemented via tags. Let a user to add tags to books and then to filter by them. So to the current checkboxes in the filter you add checkboxes for each tag, a checkbox for "no tags" and a checkbox for "select/clear all tags" .

While I know some languages don’t use spaces, words-per-minute (wpm) is the standard metric for speed reading and feels more intuitive for users. Maybe we could implement language-specific word segmentation for accurate counting?

People who study several languages will benefit from this. You study spanish. Translate paragraph to english. Find unknown world and with just one click translate it to your native language. With willbe good. Кейс на подумать. Читаю на испанском, но перевожу на английский, для практики обоих языков. На английском не все слова знаю. Хочется кликнуть на уже переведенное в параграфе английское слово и что бы он мне показал русский перевод. Сейчас приходится это через сторонний переводчик делать. Кейс не для всех конечно, но мне бы было удобней)

set same front size in setting, but present differently in Japanese books and English books. Can we make it same, or have separate setting for different languages?

Перекладений абзац на рідну мову є граматичним а це не дає можливість зрозуміти дослівно перекладене слово. Функція перекласти слово видає не той варіант що в абзаці . Пропоную в абзаці над перекладеним словом дрібним шрифтом прописувати оригінал слова. Так легше вивчити слова! .

В Smart book сейчас нельзя быстро поменять порядок переводов — чтобы это сделать, приходится удалять варианты и добавлять заново. Это долго и неудобно. Предлагаю добавить простую функцию перетаскивания (drag-and-drop) переводов внутри карточки слова. Это позволит: ставить на первое место самый точный или актуальный перевод; группировать значения по смысловой близости; редактировать словарь быстрее и удобнее. Функция аналогична перетаскиванию треков в плейлисте Spotify — просто и понятно.

I'd like to save some phrases or paragraphs to re-read in the future, further investigate about it, etc. This is a basic feature that almost every other book reading app has and I think I'd benefit greatly its overall user experience

Additional field for user comments. Synonyms. Definition. Example. Auto saving of source context. Word forms for linking different forms from text with one card. Transcription editing. Genders. Articles. Ability to quickly fill in fields using AI services.

Sync saved words between devices of a single account

Sometimes I also want to improve the original text, e.g. I download subtitles from YouTube that are not broken into sentences, there are only words but no punctuation marks. I would correct this while reading.