Jackal is most likely a typo, its makes no sense to add 3" to that ability. Both Nexos of Devotion and Sacred Cult banner are aura abilities, they affect models or units in a given range, so you would add 3" to them, with alien majesty.
AURA ABILITIES
Some abilities affect models or units in a given range – these are aura abilities. A model with an aura ability is always within range of its effect. The effects of multiple, identically named aura abilities are not cumulative (i.e. if a unit is within range of two models with the same aura ability, that aura ability only applies to the unit once).
The wording of Nexus of Devotion is wrong in the
40k app. That must be the old version. Dont use the
40k app, its junk. The new version says :
Nexus of Devotion:
Roll a D6 each time a <CULT> INFANTRY or BIKER model (other than an ABERRANT) loses a wound whilst its unit is within 6" of any friendly <CULT> ACOLYTE ICONWARDS; on a 6 that wound is not lost.