Hi 
!
If you have HA OS installed, your best option is probably to use the VS Code Addon Home Assistant Community Add-on: Visual Studio Code and use it to edit your configuration.yaml directly in the browser.
Alternatively you can use VS Code locally and connect to your HA instance, but I’m not sure what you’d need to do that. I’m sure you can find some instructions in this forum.
Another way is to use the Samba addon addons/samba/DOCS.md at 5b74a42e97eaf02bbc7bb070b4fac6f5145eb3a3 · home-assistant/addons · GitHub and mount the config directory at your local PC to manage the files.
Here is more documentation about this issue Configuration.yaml - Home Assistant
Where do you have that config.yaml from, and how did you get it parsed if you don’t access it from HA?
Regarding the title of this thread: Is there something not working about the KNX integration, or is it just missing configuration?