i also think that the primary side as conscious and the other side as unconscious is a helpful distinction. right brained (p) and left brained (j) make a lot of sense to me in my mb analysis of myself and others (extraverted perception vs introverted perception).
i think the apparent (auxilary alternative) of Te for an infj's Fe is more a haphazard combination of Fe-Ti looking somewhat similarly, i can never truly use Te to anything that is more than a remote resemblance. i can never completely table Fe, so it doesn't work simultaneously. i think the stress of the inferior is a very real and present problem for many people as well. tertiary as relief makes sense too, altho i think tertiary is capable of so much more personality definition than just a relief function (but supportive only, as awareness and balance from the first two functions swells)