Resolve 12.5 that came out in the last few weeks supports 29.97 delivery of 23.976 sources. I am thinking that 12.3.2 would be doing a motion effect type frame rate conversion which would explain the ghosting.
You do not need to convert to DF when going to 29.97 from 23.976. But you do raise I point I need to test. but I believe Media Composer multicamera just needs to have the same frame rate to be grouped, but sources can be DF or NDF when grouped by IN point. If grouping by TC, then they would need to be the same. But grouping my TC will be hit and miss anyway due to the conversion from 23.976 as there will be +/1 frame (maybe more) differences of where original and new frame boundaries lie.
My overall feeling is that when converting sources from 23.976 to 29.97 that the 29.97 be NDF as there is a known correlation of timecode should you ever need to go back to 23.976. The assumed relationship is “A” frame on timecodes ending in 0 or 5. DF would change that at every minute by two frames in the count.
3:2 and 2:3 are similar ways to say the same thing. It denotes that a field cadence has been done as part of the conversion process. To be super exact, it would be referred to 2:3:2:3 as the cadence occurs over 4 original 23.976 (24) to create 10 fields of video (2+3+2+3). You can have different cadences such as Panasonic’s recorded cadence for DV cameras of 2:3:3:2.
Michael