I also almost had a tank die on me in Haukke Manor when I first ran it after creating these macros. I tested them on myself in town just to make sure they worked but I didn't do any testing with rapidfire throwing of heals.

I've tried all of the following variations:
/micon "Physick"
/ac "Physick" <mo>
/ac "Physick" <tt>
/ac "Physick" <t>
/ac "Physick" <me>

/micon "Physick"
/ac "Physick" <mo>
/ac "Physick" <tt>
/ac "Physick" <t>

/micon "Physick"
/ac "Physick" <tt>
/ac "Physick" <t>

/micon "Physick"
/ac "Physick" <t>

And the game will randomly target me for the heal when using the macro. I notice it usually happens when you are casting lots of heals in a row, like 2+ on the same target. I had to go back to using individual heal spells for now because some situations you can't afford to let the tank die because of a misfire.