Library not syncing and adding duplicates

[ArthyxeFR]

Plan

Premium

Country

 France

Operating System

Android 7.0, Windows 10

My Question or Issue

I have multiple problems who start to annoy me and make me test other services :

- When I add a song to my library on my phone it does not sync on my computer.

- It annoys me when I listen to a Daily Mix and I add a duplicate song to my library because the application does not recognize it is a duplicate. I have the song from another album in my library and if I press the like button the application will add this duplicate to my library and I have the same song two times from two different album or one from a single. 

- And why local files with good tags don't appear on the library ? I have songs with an artist name and it would be cool to see these songs appear in the artist library.

 I know there are different posts about these issues but they are old and these features are still not implemented or these bugs still exist. I use Spotify since 3 years and my patience is at its limits. Thank you.

(Sorry for bad english)