Chromebooks do not have many of the keys found on a normal laptop keyboard (Print, PG Up/Dn, Delete). Some keys are replicated with specific keyboard combinations, e.g. Search + BKSPC = Delete Stock keyboard is mostly useful but many necessary keys do not work like Display Brightness, Volume, Delete.
There is a patch for xkeyboard-config in AUR as
Yes, it’s easy enough to install but that means it’s not available on a live session. Most users wouldn’t know of the need to do so or how. As it stands, the Manjaro keyboard on a Chromebook is inferior.