You can’t "pull the trigger" if there is nothing to pull the trigger on.
If you want to be "sudden" then you will benefit from having a stretch-and-fire triggered launch.
When you say she sits like a "deer caught in the headlights", I envision a hitter that lacks ‘stretch’ and the setup for a stretch-and-fire triggered launch.
When you say she swings lazily, you add further confirmation that SnF is absent as well as the accompanied suddenness.
Check your daughter’s sequence against the sequence of the best hitters. The odds are good that it doesn't match up. Clean up the sequence. Learn what SnF is. Embed SnF into your daughter’s swing … and when SnF is embedded into her swing, then the issue with a lack of suddenness will be resolved.
This is very good advice and goes possibly to a root issue. Since the "S" in SnF is happening for many hitters near the end of the pitchers motion around the release point (when you have little idea of pitch location) if you are not achieving "S" or coil or whatever move you call it every pitch then you cannot even worry about other aspects like fear, uncertainty etc because you are simply not ready to swing.