That is unlikely to ever happen. Macro Palettes do not have keyboard focus. They very deliberately do not, so that they do not interfere with what is happening in the target application. I could fake it somehow, and use hot keys for arrow keys, but Macro Palettes have never had any concept of “selection” so I doubt I will ever do that.
Conflict Palettes already have a mechanism for selecting the entries from the keyboard - they highlight the unique letter position to allow you to filter/select the desired entry.