Enhance Reader App: Speed, Design & Compatibility -- 2

I am seeking a talented developer to make edits to a reader I have started. The reader must support natural sounding tts in the following languages:

English
French
Spanish
Russian
Portuguese
Arabic
mandarin

If needed I can provide an api key for and from apis that would help us with the project but themselves are not expensive.

I am looking for automatic word highlighting as the text is read aloud as well, each word should be highlighted as the word is said outloud by the tts.

Key Requirements:
- Incorporate animations and transitions for a more dynamic user experience
- Ensure compatibility with .txt, .pdf, and .epub file formats

Ideal Skills and Experience:
- Strong experience in software development and optimization
- Proficiency in UI/UX design with a focus on modern, minimalist aesthetics
- Ability to implement animations and transitions effectively
- Experience with file format compatibility and reader applications