all depends on the wording mate,
now l don't play SW but they have a few of these items and skills so this is how it works in the games l played with my GK.
some say the Target unit, where it lands or cast from and if it effects.
Stormcaller has his "anyone who cast within in 24 incs" so it does not matter as long as the user cast within 24 for him.
with talisman if the unit gets a "effected by the psychic skill" so if you cast a buff on your self it won't trigger. However if part of the spell lands or "effects" that unit (even while still hitting a unit without it) with the talisman and he pass his 5+ then its gone.
other's say "spells targeting the unit" so if you target one unit and it just happens to scatter on to the other unit with this rule it does not matter because it did not "target them"
like l said before l don't own a SW dex so l can't check the wording but next time recheck your friends, it should be clear :D.