The Runtime Audio Importer plugin imports the sound wave not as a standard USoundWave, but as a UImportedSoundWave, which has its own methods and described here.
To begin with, the most important thing for playing ImportedSoundWave is the "Start Time" value in the function for playing the sound wave must be "0" (this can be any function such as "Play Sound 2D" or "Play" from Audio Component).
Due to the use of a procedural sound wave, to rewind the playing time, you need to use the "Rewind Playback Time" method, which rewinds the sound wave for the required specified time. You can call this method even before the sound is played, so that the sound starts playing at a specific time.
You can also get the current playing time of the sound wave in seconds or as a percentage using the "Get Playback Time" and "Get Playback Percentage" methods.
To check if the audio playback is finished, use the "Is Playback Finished" method
To track the end of audio playback, bind to the "On Audio Playback Finished" delegate
If you no longer need Imported Sound Wave, you need to clear the data in memory for optimization. To do this, use the "Release Memory" method. Even though the importer sound wave can be destroyed automatically, during garbage collection on "Begin Destroy", for the sake of optimization, it is advised to clear the memory manually.