Custom Field to Store a User Modifying the Project Task Finish Date

Hello All,

I am working on a development for my organization where our company wants a custom field that will store the User name who modified the Finish date in the Project Shell. I have taken a look at the Project end dates and created a field inside of a Dynamics CRM form to house this change, but when the change is made on the project shell, it doesn't trigger the flow if the change is made from there. Does anyone know if this customization is possible with Projects For the Web?