Ok, so I just read the social conflict section and I think this is where we are getting stuck.
Social conflicts tend to vary more than physical
conflicts do in terms of what constitutes
the nature of an attack or maneuver, and they
require that the participants be very clear about
the nature of the conflict and what the conflict
is intended to do. Intimidation has little place
in a conflict about trashing an opponent’s reputation,
but a conflict about winning the favor
of a particular patron might open up several
avenues of attack depending on the resources
of each participant. Likewise, someone trying
to provoke an opponent into hostility probably
won’t use Rapport.
So a social conflict varies enough that any one action (mundane or magical) is never going to be appropriate in all situations, or even most situations. There is no blanket rule about what works and what doesn't because the intent of the conflict can be entirely different in two different situations. As it has been said there are some situations where pantsing someone will be effective and some where it would do nothing at all. Futher:
Ultimately, a good guideline is that an attack
is any action meant to directly take someone
out of the conflict in one way or another, and a
maneuver is any action meant to provide a situational
advantage to make those attacks more
effective. Taken together with a clear picture of
what the conflict is about, this can help provide
a guide for what kinds of skills can be used.
Which means that it is also situational as to whether something is an attack or a maneuver, and the same thing could be both in different situations. I can definitely see situations in which a pantsing could be used to attempt to take someone out (in fact in the arena you usually see it, I.E. secondary school, that's most often the way it's used), and other situations where it would serve to improve another's roll, while still others it would again do absolutely nothing. It's all situational. Finally:
As with parsing out the combat actions, figuring
out what stress and consequences mean in a
particular social conflict can take some wrangling
and, as before, looking at the nature of
the conflict is the best place to start. Remember
that consequences are meant to represent the
outcomes of a conflict that “stick” to the participants—
as soon as the scene’s over, anything
recorded as stress is really just narrative color.
In terms of consequences, the easiest way
to represent the effects of social conflict is
through negative emotional fallout—aspects
like Stressed Out, Crappy Mood, Nervous,
Edgy, and Guilt-Ridden can all come into
play later in dynamic and colorful ways. Another
potential option is to let the consequences reflect
changes in how other people perceive the character
after the conflict shakes out. If a character’s
reputation is ruined, representing that with
a Smeared Name aspect can lend mechanical
weight to what might otherwise be just a
narrated effect.
Sometimes, the most important effect of
a social conflict comes from the new circumstances
the event brings into the character’s
life—if a character has a significant other,
falling for a seduction attempt could create
Relationship Doubts or something similar.
Play around with any and all of these types of
consequences to give your social conflicts a far reaching
impact on play.
So there can be some overlap between mental and social consequences, however I think of mental as a step above. Social consequences may put you in a bad mood, even a really bad mood, but mental can put you in the hospital's psych ward.
In conclusion the answer to the question of "By RAW can magic (or any action of any kind) cause social stress without breaking the laws" is yes.....Sometimes.
Edit: Of note sorry for the long post.