Hi Ez,
Since you are able to see the field in BUT00, you created it using AET in right way. Just that you did step-1 of creating the field and missed step-2 of making that field available on UI. You can make the field available on UI by two different options as below:
1. Using AET - Open the BP on web UI and go to personalize option, add the field and save
2. Using component workbench - Use t-code bsp_wd_cmpwb on GUI to open the component, select the view, open the view configuration, go to edit mode bring the field on the view configuration from available fields and save.
In both options you will have to provide configuration TR.