I believe this was available in Deezer Web before, please correct me if that is not the case.

It would be nice to be able on an album page (e.g. this) to sort tracks by popularity by  clicking on the popularity (“POP.”) list header.

The same for “TRACK” would trigger alphabetic sorting.

This would be equivalent to the functionality in the “Top Tracks” view for an artist:

“Top Tracks” currently allows sorting by track name, album name, track duration and popularity.

Except for the sorting by album name, all of these should IMHO be available in the album view as well.