Complex sentence: Lachman noted that had Blavatksy spent time in Tibet, then she would be "one of the greatest travelers of the nineteenth century", although added that "in all honesty I do not know" if Blavatsky spent time in Tibet or not.
Split into simpler sentences: Lachman noted that had Blavatksy spent time in Tibet, then she would be "one of the greatest travelers of the nineteenth century". Lachman stated that "in all honesty I do not know" is Blavatsky spent time in Tibet or not.