For frame rate conversion
1) Import the Premiere Project which creates a comp with sliced layers stacked
2) Reset Comp (comp settings to wanted FPS)
3) Apply Twixtor to top layer (set Input FPS to original FPS)
4) Copy Twixtor
5) Select all layers (then unselect the top one where Twixtor is already there)
6) Paste Twixtor – you now have Twixtor on each layer and FPS conversion for the whole sequence
— and in AE the audio still matches
Pierre