Very sorry to hear.
Unfortunately it's a known issue in Logic Pro that you can get unexpected behaviors when multiple projects are open. I wasn't aware of the behavior you're describing, but one that has been widely reported multiple time here and elsewhere is the scrambling of channel strips playing wrong instruments etc. 😞
I'm not sure which display you're seeing, but for example the bars and beat display rounds up the values. To see the tempo list, at the top right of the main window, click the Lists button then the Tempo tab:
Yes or similar to @Dan Banan's last suggestion, just drag and drop the audio files to a track and you'll get that dialog pop up asking you if you want to place each file on its own track.
Ok unfortunately I can't make it work so I recommend that for that project you just create a software instrument track with a MIDI region with notes on every beat, looped, so that you can use that track as a metronome.
It's either that or reimport all your tracks into a fresh new empty project to rebuild it.
Could you share that project file? Not the whole project, only the project file. You can use a service such as WeTransfer or Google drive to share the project.
No, you don't need to route that MIDI Metronome Click object.
Now in the Mixer when you click the "All" button at the top, you still don't see a Click channel strip?
Can you share a screenshot of the Stereo output (or other output) channel strips as well as one of that summing stack (open) in the Mixer (during playback so that we can see the meters active)?