You wish to create a custom format for your Access logs, however some of the ELFF formats do not have a corresponding custom format
In order to add a field to the custom format you will need ones that begin with % or $.
Since fields like cs-uri-scheme do not have a custom format, adding cs-uri-scheme will not return a value, it will just display the field name itself. In order to display a value you will need to edit the format to the following
Other examples; $(c-ip) $(cs-username) $(localtime) $(cs-request-line) $(sc-status) $(sc-bytes)