A nice thing about the Lithuanian yeshiva approach it that it tends to combine numinous holy and powerful experiences of learning and keeping Torah with great intensity along with a remarkable lack of religious delusions.  In fact, anything that even seems like  grandiosity is rigorously exuded.
To some degree this maybe over done. They tend to err on the side of caution. But judging by how many delusional religious fanatics there are than wander into Litvak yeshivas it seems that they are justified.

This leaves us with the question how to discern between delusion and authentic religious experience?
Probably there is no way.