You keymapped that to the “videos” window which is where you land when you click on TV or movies from the home screen. If you look at what I posted yesterday you will see that “FullscreenVideo” is the window name you should be using.
The keyboard marker is correct for CEC use.
Thank you so much!
The videos item is in the gen.xml file created by keymap editor and which I have hand edited with your key id values for the color keys I could not check myself.
Now I have fixed that and used the command:
kodi-send --action=reloadkeymaps
to activate it whereupon the color keys work just like I want! 
I guess I can rename the gen.xml file to something else so it won’t be overwritten by keymap editor if I use it in the future?
You can rename it if you want, but that will not fix the issue of keymap editor removing your changes if you open it. Basically Kodi just opens and takes in any and all valid keymaps placed in that folder in alphabetical order with subsequent files taking mapping precedent for any conflicts. As such keymap editor takes anything there other than gen.xml and renames them so they don’t load and cause any conflict. If gen.xml contains any code that the add-on doesn’t understand it will either just rename the file and make a new one or mangle the code inside breaking the keymap depending on what manual edits were done. If you happen to run into this then you can just go to the keymap folder and you should see pretty easily what was done and just rename files back again.
OK, that is why I see these strange variants of files then…
Meanwhile I tested on my other OSMC installation (on an older RPi2B) in the guesthouse where the display is a Philips 32" LCD TV and here I figured I had to check the codes using the editor. The Philips remote works OK for normal Kodi usage but…
It turns out that the color buttons are seemingly not transferred to Kodi at all via CEC, instead they bring up TV specific pages. So here I am out of luck adding the skip steps to color buttons…
If your using an OEM TV remote then your kind of stuck with what buttons the TV forwards and which it doesn’t, since there is no way to dictate what it forwards via CEC and which it doesn’t *. I personally am not a big fan of trying to remember odd mappings and I have a strong preference towards things like the context menu popping up in Kodi when I press the menu button and the info button bringing up the information window in Kodi. To rectify this I use universal programable remotes and I move the buttons around to get me where I want to go. For example on a Toshiba TV neither the menu or info buttons forward via CEC but I have both the chapter +/- and ff/rw buttons that do and they are a bit redundant as video navigation in Kodi is programed to the direction keys. Therefore I just do things like program rw to the menu button and ff to the info button on the remote control itself and then keymap Kodi so the actions line up with my altered mappings on the remote. I also program the remote so the rw/ff buttons do nothing when you press them as that would be rather confusing.
The other thing with universal remotes is they can sometimes have things that forward that your original remote does not. For example the OEM remote for one of my Toshiba TV’s has a single play/pause button and Kodi picks that up as play/pause. However the profile that my Harmony remote uses on that TV actually has discrete play and pause buttons that Kodi picks up as such. Since the Play button maps in Kodi to the same key id and is default keymapped to a play/pause action that allows me to use the pause button to do something else with. I also found on that TV that the Harmony profile did not have a mapping for the eject button and that was something on the OEM remote that did actually forward via CEC. This is where a learning remote comes in handy as you can then combine codes in from more than one place.
*This may not be 100% true for all TV’s, but I’m not going down that rabbit hole in this thread.