I upgraded from 2013 straight to 2018 no problem, I had a good backup and made a copy of my company just in case.  The only problem was updating my second user because you have to log in the computer as the user that was logged in when that account was put on that computer and that employee  is gone and her profile had been removed from my server and her computer.  My IT had to fix that.

You can go from V12 to v2018  See Knowledge Base article #47358 How to convert from BusinessWorks version 12 to the current version of Sage BusinessWorks Accounting 

Thanks,

Coleen