60fps vids in 30fps comp - audio out of sync

If the speed is not right for either the video or the audio then the footage is not being properly interpreted. Check File>Interpret Footage and make sure that the footage is interpreted as it is. I do not think you have a good understanding of how frame rates work in NLE's or compositing apps.

The biggest clue to this error is when you said:

Back then I did it in AE CC 2015. I used 60fps footage in 30fps composition, audio fits perfectly, in plays at 2x speed just like the video (audio embedded in video).

That can't happen if the footage is properly interpreted. Put 10 seconds of footage that was shot at 60 fps and interpreted as 60 fps in a comp that is 30 fps and it will still be 10 seconds long and play back at normal speed. Put the 60 fps footage in a comp that is 10 fps or 99 fps and it will still be 10 seconds long and playback at normal speed.

If you want 60 fps footage to play back at 2X speed then you have to interpret the footage as 120 fps and put it in a comp of any frame rate. If the interpreted frame rate in the footage properties matches the frame rate that was actually used to shoot the footage then it will playback at normal speed no matter what the frame rate of the comp, or the Sequence in a NLE is. The only difference will be how many of and how accurately the original frames in the footage are used in the comp or sequence.

If the footage is 60 fps and if the comp is 30 fps then the comp will just skip every other frame. If you interpret the footage as 30 fps Then the comp will display every frame and the speed will be half. One second will take 2 seconds to play back.

There is a chance that the footage you think is 60fps is actually 59.94 fps so to perfectly playback every other frame and keep the speed normal and not end up with interpolated frames the comp should be 29.97 fps to avoid frame blending. If the footage is interlaced 59.94 it could actually be interlaced and the the true speed of every pair of fields (two fields make a single frame) would be 29.97 interlaced frames per second. The point is that you absolutely have to know what the actual frame rate and type of frame capture is to get footage to play back at the correct speed. If you want to accurately playback footage at 2X speed then you have to double the actual frame rate in the Footage Interpolation settings or have the footage properly interpreted and use time remapping to accurately change the speed of the playback.

As long as AE is up to date (there were some bugs in footage interpretation in previous versions) your problems are coming form not knowing exactly how the footage was shot and not correctly interpreting the footage frame rate. It is entirely possible that AE is misinterpreting the metadata in the footage and reporting an improper frame rate.

If you fix the frame rate interpretation and still have problems then let us know. Several video formats can be misinterpreted so the audio and video are not in sync, but most will maintain sync if you change the interpreted frame rate. I can also give you a fool proof way to find out if your footage is interlaced and a perfect way to remove the interlacing.