As noted in the review, repeatedly editing a video in BB Flashback resulted in
the loss of audio/video synchronization.

More specifically, in a movie with many small audio tracks, after a certain
point, the audio output began to lead the video (presumably by an amount equal
to some previous editing operation). This was despite the fact that the movie
played back properly within the authoring application.

Deleting and reinserting audio tracks made no difference.

A successful workaround was to select all the frames of the video, and export them
to a new project. In the new project, the audio tracks appeared earlier than
they did in the original project. At this point it was possible to reassign them
and generate correct output.