Help / Updates in the Elements Editor is supposed to find updates and should work for getting ACR 8.3.
it tells me my editor is up to date , camera raw file is 18.104.22.168 - either way I cannot see raw files from a canon s120
Try the ACR 8.3 CC installer link from the following Adobe plug page, and see if it recognizes Elements:
And/or this information is from the last message in the above page, and would be for Photoshop, but perhaps it works for Elements, too:
Try Help->Update again after deleting following folder contents:
/Volumes/%Volume Name%/Users/%Username%/Library/Application Support/Adobe/AAMUpdater/1.0
ACR Installer QE
There is probably way to extract the ACR Plug-in from the setup.zip downloaded in the CC on the #notconnected page linked, above, and manually place it in the proper place, but try the above before coming back here for those instructions.
I currently have ACR 8.2 running in PSE11, and I just saw another forum post about someone getting the ACR 8.3 CC installer to update PSE11, so I expect it'll work for PSE12.