When entering transactions, the tab key allows moving from one field to another, and it is possible to enter direct, eg date, time, payee, value.
But the CATEGORY field, even when highlighted by TABbing from the previous field, requires a mouse movement to select the field, before starting to type.
Now some people will use the mouse all the time, and use that to select from the list of categories, but I use keyboard shortcuts whenever possible. Once I have used the mouse to click in the Category field, I then press a letter key, and use the arrow keys on the keyboard to select the required category. I then press ENTER, to select it, and TAB on to the next fields.
I hope this helps.
You can select the accounts using using Space bar too. Even when selecting categories - it's just that Enter works there as well.
However, I do see the inconsistency you're reporting. Thank you for bringing this to our attention! I'll note it down to our team for further investigation!