I have used various low end video editors, sony movie studio and vegas. I believe the problem you are having is how to synchronize the video event with the sound event. So that when (example) someone flicks the wrist, you hear the sound on the audio.

A few assertions
1. if the sound and the visual event (i.e. flick the wrist and hear the bell) are off by less than ~50ms, your eyes will think they are simultaneous. So you only need to be matched to ~50 ms.
2. 1 video frame is 33ms, so if you are +/-1 video frame, you are ok.
3. cameras have a pretty good internal sense of timing. So if you can line up the audio of camera 1 and the video of camera 2 in your video editor at ANYWHERE along the video track, most likely they will be lined up everywhere along the tracks. Cameras record rates dont drift that much.
4. I have been successful in multi-camera shoots to just use the audio of one source for all the video angles. Pick the best audio and stay with it.
5. Seems you have fragments of video that you are piecing together (20 min snippets). that can be a pain; but if you have a common element in the snippet and some other video track (someone sneezing, turning their head etc), you can use the video cues common to both video track to lock in the relative positions. That will also lock in the audio tracks (see #3 above). I had one job where only the audio was continuous and had like 10 different video clips, no audio.

So I would start with one baseline (B) video or audio track and then bring in each one (E1), find an audio or video cue to line up with the main track and then lock that down. If you can't line up B and E1, bring in E2 and then lock that down. Maybe you can then lock down E1 and E2.

BTW the reason for the 30 min limitation on video recordings (aside from disk space and sensors overheating) is - taxes. Import tariffs on video cameras are higher than on still cameras. A video camera is something that can record more than 30 mins.

Good luck!