I think that there should be the possibility to force the change of the category for every account. It is quite common the “improper” use of some modules to face some specific need, so, for example a capital account can not always fall under financing activities. Manager should leave the freedom to change also to move some bank/cash accounts from cash (opening/closing) to other categories and vice versa.
Secondly, I think that there should be the possibility to create subcategories under the three main categories, to sort them and to collapse them, if needed, in order to shorten the list.