What would you want to do with the knowledge of which questions have been answered wrongly? To identify them is not a problem (with advanced actions) as you can read in this older post:
As you said, all of the information gets transmitted to the LMS (if you have specified it to be reported in the Quiz settings in Captivate).
AFTER that point. whether or not you can get meaningful reports about which questions were answered correctly or incorrectly is dependent entirely on what reporting options your LMS gives you. The data is all in the LMS database, but most LMSs only have very basic reporting, focused more on pass/fail and completion statistics.
If you want more granular reporting, you may need to hire a programmer capable of writing the necessary SQL code to generate custom reports.
if you put this script onEnter of each quiz you can populate you variable with true or whatever you want. The part of the code where to enter your variable is bolded.
window.cpAPIEventEmitter.addEventListener( 'CPAPI_QUESTIONSUBMIT', interactionFunction, false );
function interactionFunction( e )
if ( e.Data.questionAnsweredCorrectly === true )
window.cpAPIEventEmitter.removeEventListener( 'CPAPI_QUESTIONSUBMIT', interactionFunction, false );
window.yourVariable = true;