Can astral travel put a person at risk of losing their tether to their physical body and not return, in effect triggering their own transition, or worse, becoming an earthbound lost soul spirit?

Astral travel does not normally result in transition, but this can happen if a person is too severely traumatized during an astral travel experience. In the same way, a living person can be, in effect, scared to death by too great a trauma or too horrific a circumstance and they elect to leave rather than undergo further torture. This can be a blessing when it is appropriate, and the lesser of evils. Certainly it is never Creator's plan for people to suffer and be in endless torment. So death under those circumstances, in the absence of a better solution, can be a true blessing and a release from further harm to the soul. The best policy is to avoid such circumstances altogether by not taking undue risks and putting oneself in harm's way. All such excursions using astral travel need to be done under high-level protection, requested of the divine realm, to implement and monitor so the journey can be safeguarded, and the soul kept safe at all times from any assault. The tether cannot be severed unilaterally by dark spirits, but this can be surrendered by the self under extreme circumstances, and that may well be granted by the higher self because of the dire condition of the human extension being separated and then at the mercy of dark forces brutalizing them.