There is no Tibetan book called the Tibetan Book of the Dead. The title is a Western invention, and the object most readers have in mind is a particular English package rather than a Tibetan classic.
What the Tibetan text is
The core text is the Bardo Thodol, "Liberation through Hearing in the Intermediate State", a set of instructions read aloud to a dying or newly dead person to guide them through the after-death visions toward recognition and liberation. It is a terma, a revealed treasure, attributed to Padmasambhava and brought to light by Karma Lingpa in the fourteenth century, and it is one part of a much larger cycle of funerary and yogic material, not a freestanding scripture with the canonical standing the English title implies.
Where the famous book comes from
In 1927 Walter Evans-Wentz published an English volume and gave it the title The Tibetan Book of the Dead, modelled on the already-famous Egyptian Book of the Dead. Evans-Wentz was a Theosophist, did not read Tibetan, and worked from a translation by a Sikkimese schoolteacher, Kazi Dawa-Samdup; his framing overlaid the Tibetan material with Theosophical ideas of a universal secret doctrine. Later editions added a commentary by Carl Jung, which read the text as a map of the psyche, and the book went on to a second career in the 1960s as a psychedelic guide.
Donald Lopez has traced this history in detail. The point is not that the Tibetan material is inauthentic, the Bardo Thodol is a genuine and important text, but that the book carrying its name in English is a hybrid, and much of what Western readers take to be ancient Tibetan wisdom about death is the sediment of a twentieth-century encounter.
Why it matters for the doctrine
The English packaging encourages exactly the two errors the entry warns against: that the bardo is an afterlife one arrives at, and that its trials are a judgement undergone. The Tibetan instruction says the opposite, the appearances, peaceful and wrathful alike, are the mind's own projections, and the whole purpose of reading the text aloud is to prompt the dead person to recognise them as such and wake up.