Hi Jethryn
So I Think what you are trying to achieve is this :
It is a little fiddly, but possible in Numbers. We are going to make use of Numbers ability to allow custom value labels, by default value labels shows the value of the data element, but you can also define custom value, including text.
First Create your stacked data chart as usual.
Then Select the first row stacked chart series, in the screenshot above the first series is 'West'. Click the Chart Inspector in the Inspector Panel, and turn on the checkbox for value labels. By default this will show the value, but click on the dropdown format box and choose custom.
This will open a custom format panel, as shown below. Enter the Label that you want it to show in this case 'West' and then Click ok.
You will then need to repeat the steps for each item in your X axis to create all your custom labels.
Hope this helps.