Macros, please fix them or indicate if you will not.

[HyoMinPark]

Hmm what I would try is maybe just adding a short delay after the verfire cast in the macro to see if that prevents the issue. Something like...
/micon "Verfire"
/ac "Verfire" <wait. 0.5>
/ac "Verthunder"

Obviously that's not ideal but it might work as a band aid for the time being. It's really too bad that there aren't any exception commands, like a "cast this unless this is available" type thing.

Unless they’ve changed it, you can only do whole second delays, so you will have to do <wait.1> instead—which will add up over time and result in lost casts, which results in lost damage. That being said, I recommend not using macros for combat classes except for things like <tt> abilities that are generally placed on a tank (e.g., Palisade, Nature’s Minne, Apoc, etc.). Some mouse-over macros for heals are fine as well, from what I’ve seen. But, even then, they can be wonky; those are not as bad as trying to macro entire combos, however.