@back skill_dokkev_passive02.LineReveal time:0.2 id:cutscene wait:false scale:1.1
@back skill_dokkev_passive02 time:1.2 id:cutscene wait:false pos:45 scale:1.1

I wrote the following code.

I want the background to move at pos:45 and be applied with LineReveal effect.

However, the LineReveal effect does not apply when you enter the code.

How should I modify the code?

You are immediately cancelling the transition by adding wait:false at the end of the first command and modifying the same background with another command. It's also not possible to transition from/to the same appearance.

I tested this code in the demo project and it works:
@back Desert
@back Forest pos:10 transition:LineReveal time:3
@stop