It’s probably better to take a step back.
Just leave the gerber viewer as a viewer, to check things before you send the files to a fab.
If there is any problem in the gerbers, it is very likely it is better to fix it in the PCB editor and then create a new set of Gerbers (that is just a few mouse clicks).
The combination of PCB and Footprint editors make KiCad quite capable of all sorts of edits.
On top of that. You can also export a set of Gerber files into a PCB project. This is still a conversion, it it is a viable option. I wrote an FAQ article about this some time ago: