When you are looking for a category using VE, the list is limited and user have no idea about it.
For instance, typing "Série télévisée se déroulant en A" on French Wikipedia displays a limited list, ending with "Série télévisée se déroulant en Alabama", skipping places beyond like "Série télévisée se déroulant en Arkansas".
You don't know how many letters remain to be types to finally find what you are looking for, also because of T187341: Categories dropdown should be larger to ease categories' selection. So, at the end of the dropdown, it should be indicated something like 265 categories listed, please type more" or something similar. That's the case when you search for categories: the number of results is displayed at the top of the page.
Solve T59302: Suggest case insensitive results when searching for categories to add would help as well.