Thanks for your using Fiddler Everywhere and for logging this feature request! At this very moment, there is no option to create custom columns in FE client but I've marked this one as a feature request to be discussed in one of the upcoming planning meetings. I will update this thread once we have more related information about a possible implementation.
Posted on:14 Jul 2020 23:17
Can I add columns by editing one of the local files for Fiddler Everywhere?