Hello Maffey,
as far as I'm concerned, this feature has not been implemented in jisho.org yet. However, I made a userscript that enables this functionality (it has some limitations though, the most important being it does store the favorite words list locally and thus it does not keep the same list across different devices). If you usually use jisho.org from the same device and you are familiarised with browser userscripts, I recommend you to give it a try. You can find the link to the userscript as well as further info in my previous posts about it:
https://jisho.org/forum/56ab72d3d5dda74c8e00015d-save-search-history-and-export
https://jisho.org/forum/5c478f35d5dda7452e000070-saving-words-slash-favourite-words
Kind regards.
Can somebody help me with the meaning of this ? 信夢愛喜
Favorites category
Since there are already accounts available, could it be possible to implement adding words, kanji, etc. to favorites? Or is it there already but I'm just missing it?