If a statement has:
- The verb "failed"
- An activity type of "cmi.interaction"
- a result success of "false"
The activity stream will then display as in the screenshot attached. You get a similar thing with "successfully passed"
IMHO the adverbs "correctly" and "incorrectly" should only appear if the verb is http://adlnet.gov/expapi/verbs/answered.
There is a counter argument that statement viewer is for more technical people who may care more about the information than the grammar and that the viewer should continue to behave as it does.