There is function to get human-readable key name — OS.get_scancode_string()
If you using physical keys, try this:
OS.get_scancode_string(InputMap.get_action_list("interact")[0].physical_scancode)
Elif you're using regular keys, it's better to use this:
OS.get_scancode_string(InputMap.get_action_list("interact")[0].physical_scancode)
If neither of them works, maybe the problem in something else. Post the code where you trying to use this text.