Keymap editor does not have support for longpress functions so this would have to be done with manual edits like you started. The issue I see here is that you assume the home button is mapped to the home key but it is actually “escape”. Additionally I’m not sure “previousmenu” is the correct action in this particular situation as it seems like “back” would be more what I would assume. As such you would be using something like…
<escape>back</escape>
The names you would need to use for the mappings as well as other information on this subject can be found in the following thread…