i guess "reversing time" was not clear. as you have found out triacs and scrs do not turn off after they are turned on. that is they stay on until zero crossing. sounds like you are turning it on, then waiting for certain value (current) and trying to turn it off. obviously this does not work. you have to change the order...
detect zero crossing, fire triac with some delay from the moment where you detected zero crossing.
delay has to be adjustable in range that is 0...T/2 (or 0..1/2f).
initially you can start with larger delay (so triac conducts only near the end of AC halfperiod),
you need to measure current and if the measured value is below the setpoint, reduce delay, if it greater increase delay.
and this is how 'time reversal' works, (actually only graph looks time reversed):
you turn triac on mindway into halfperiod, and let it turn itself off at the zero crossing.