Hi acornbringer!
I've actually made a coin flipping game before and I tried a few different things that worked well
1.
Apply an impulse force along the world Y axis, and in that same action put a wait for about .3 seconds or so? Just enough for it to be up in the air THEN have it go to a state that applies the torque impulse like you're currently doing
that should do the trick.
2.
The other way to do this that's less physics heavy but also looks fun (and is maybe more the style you might be going for). Is to apply an impulse force along the Y like the previous step with a wait, but then in the next state use an random float action, and generate a float between 400-1800 or so? Then use a Set Vector XYZ action to a vector3, and plug that into an iTween Rotate Add action or similar to rotate the coin a random amount while it's in the air. This is definitely less physics looking, but has a good snappiness to it
I think I forgot in the GIF, but you can either use the time OR the speed depending on the look you're going for xP
**random notes
As I'm sure you know from the dice you've made, there's a bunch of ways to add some fun little randomness to the flip too
like height it starts from, force applied up as well as spun etc. Always nice
-craigz