When impprting the footage use the interperate footage dialog and just have ae see the footage as 30fps. Over 16 seconds it wont really drop that many frames anyway so you will never notice. My answer assumes that your footage is true 29.97 and not 24 with 3:2 pulldown added.
yes its true 29.97, after.
@ 29.97 fps: After 16 seconds it would have played 479.52 frames
@ 30 fps: After 16 seconds it would have played 480 frames
So the difference would be half a frame in worst cases, right?
But shouldn’t the audio always be in synch with the video of the imported movie since they belong to the same file and thus the sound is “baked” to the images, so if stretched in a new composition they will stretch together? doesn’t the new composition’s fps become irrelevant when it comes to the video/audio synch of the imported file?
And what’s the use of choosing “conform to frame rate 30 fps” in the interpret footage options ? how does it help in keeping video/audio synchwhen AE gives a warning saying: “Audio may not be synchronised”?