I don’t know Kanata, but you need to find out which key codes are sent for the multimedia functions in order to remap them. This file [0] (linked from [1]) contains the key names Kanata knows, and it has entries like “VolumeUp”. You could try to remap those to the respective function key.
There are some keyboards, however, which send multimedia commands via USB “out of band” from normal key codes, and which therefore cannot be remapped that way.
There are some keyboards, however, which send multimedia commands via USB “out of band” from normal key codes, and which therefore cannot be remapped that way.
[0] https://github.com/jtroo/kanata/blob/main/parser/src/keys/mo...
[1] https://jtroo.github.io/config.html#key-names
In case you are on Windows, I would recommend SharpKeys [2] for basic remappings.
[2] https://github.com/randyrants/sharpkeys