When you start typing in the categories box and the dropdown is filtered to values that starts with the typed value. It should filter to values that contains the typed value.
If I want to add the category Womens Clothing > Underwear > G-String I should type G-Str and get 2-5 to select from. If I type Wom I get 100+ subcategories under Womens Clothing and have far to scroll to find the correct subcategory.
Also I have a lot of manufacturers and the uniqueness lies att the end of the name so filtering the dropdown with contains instead of starts with will make it easier to find and select the right one.