Chang Activities View Header Name Supported/Unsupported way?

Hello,

I'm aware that changing the display name of the field changes label on both form (unless you change on field properties on form) and any associated entity views. I'm specifically looking Activities entity column header. OOB you cannot change the display name of the "Last Updated" (modfiedon) field. I showing Activities subgrid on a form and I'd like the column "Last Updated" to display "Date Completed". Is this doable support or unsupported way?

Thanks,

M