Looking to split audio from different sources that's become enmeshed in recovery

Question

My Zoom H4n somehow decided it didn't want to properly save two recordings this weekend, leaving me with four zero byte files (which I have tried any which way to open/convert, but nothing was working).

I then used CardRescue to scan the SD card for any audio it could find, and - lo and behold - I got .wav files! However, instead of two files for each session (one was an XLR output from the desk, the other the on-Zoom mics), or even a nice stereo with one left, the other right, I have a mess.

In importing as raw data to Audacity (the rescued .wavs themselves do not open), the right channel has the on-Zoom mic audio, with intermittent silence. The left has the on-Zoom audio, followed by the same part of the XLR input audio. This follows the same pattern as the silences.

I have spent hours chopping up in Garageband, but as it is audio for a video, it needs to match what 'really' happened perfectly (I appreciate for a podcast/audio-only I could relatively simply take away the on-Zoom mic audio from the left channel). I began attempting to sync the mic audio to the on-camera audio (which, despite playing around with settings is as unusable as it always is) but because it's a pattern, can't help but wonder if there's a cleaner fix: either analysing the audio somehow as there are clean lines if I look at the spectral data, or a case of adding a couple of numbers to the wav's binary that'd click the two into place?

I've tried importing to Audacity with different settings, different offsets - this has ended up in either slow audio, fast audio, or heavily distorted audio (but always the same patterns with the files).

I use a Mac (and don't know any PC users close by!) so any software suggestions will need to run on Mac. However, I'm willing to try just about anything that's not dragging tiny clips.