iCloud won't transfer manually added music
I realise this is months late, but iTunes was never designed to synchronise Libraries in that way. iTunes Match is the closest you will get to automatic synchronisation.

The simplest way to do it is to manually add to each Library. 

Even if both Libraries use the same actual source, such as NAS storage, or one of the 2 machines you mention, the Playlist data will not update to reflect the addition of a tune to the other machine - the file would be there, but the player wouldn't realise.

It is possible to manually transfer the playlist from one machine to another in such a case, but it needs re-syncing every so often, it can't be automated. The file-paths are absolute rather than relative, so this requires some patience &amp; a lot of find/replace, then must be re-imported to the other machine. For your scenario I don't think that would be the way to go, but I can add instructions to this answer if you need.