Your proposed solution works. Thank you!
For the record, here is the process:
In the Joomla URL, languages are specified by "lang=". I am using English and Japanese, so for English the URL shows "lang=en" and for Japanese it shows "lang=jp"
In Community Builder Tab Management I select the tab that I want to only show when viewers are on the English version of the website. Under the Integrations tab, I choose "CB Conditional" and then set as:
Display = Tab conditional show
Conditions are
Field = Value
Custom Value = [get_lang]
Translate Custom Value = No
Operator = Equal To
Value = en
Translate Value = No
For the tab that I only want to show when viewers are on the Japanese site, all settings are the same EXCEPT change Value = en to Value = jp