Hi Zaghman,
I'm not aware of a proper static header for the RowRepeater too. One workaround might be to switch off all headers of the RowRepeater (as it is shown in https://sapui5.netweaver.ondemand.com/sdk/#test-resources/sap/ui/commons/RowRepeater.html ) and add the row template as a separate control before the RowRepeater itself. Of cause, if you need the headers, or parts of it, this is not an option.
The example data that you picked could as well be displayed in a table control. Is this not an option for your case?
Regards, Frank