Your configdir.ini file looks fine.
This can be a little bit confusing, so let me make sure we are on the same page.
Unlike my other programs, for LBC, when you specify the configdir.ini override, you are telling it where to save its basic options file, and a .mcp (project) file which tells LBC which .mcfg launchbar files were last open.
So to test if its working you should log in to each user account, run LBC, and then load whatever mcf launchbar files are appropriate for that user. Then exit LBC. Then do the same for the other user account(s).
What you should see is that the different users LBC will remember that they had different files opened.
Put another way, LBC will not stop userA and userB from having the same launchbar files open -- that's up to you.
But what it should remember, when you make the change in the configdir.ini file as you have, is that different users had different files loaded.
Can you check that and then let me know if it's not working?