To answer you second question first, you should say 'the Hopu and Bessert vs France case'. The noun in this sentence is 'case', and it should come with the definite article 'the'. However, when talking or writing about the case, you can simply say 'Hopu and Bessert vs France' as in the line you quote : ' However, the effectiveness of the reservation was reconfirmed in Hopu and Bessert v France '. The word 'case' is not used, so you do not need to use 'the'. This style of reference is conventional in legal writing. Now to the first question : when referring to a process or procedure it is allowed in English to omit the article 'the' in certain contexts, and this is one example. You could still use the article, and it would also be correct : ' after the publication of General Comment 24 '.

You could add "the" if you wanted and the sentence would still sound find. When you use the word "after" it's not required, the article is implied. So you could say, "after accommodation costs it is around £20" or, "after the accommodation costs it is around £20" and both sound equally acceptable. "The Hopu and Bessert v. France case" is fine. You could also say, "the case of Hopu and Bessert v. France" or just, "in Hopu and Bessert v. France."