Tunes disappearing and or reverting to older versions

Normally I would just get lots of duplicates but lately it seems like songs that have been edited on one device then shared with other devices then sent to friends and mailed back with new changes will actually revert to an older version rather then add a 1 to it or two 11's or three 111's etc.

Another strange thing happened . I forgot about sync and emailed a set list to myself then ended up with two setlist (the emailed and the Synced) but they had identical names. A 1 was not added to the duplicate.
The only difference was for some reason one of them only had 7 songs in it and the other the full 29.

Songs are also just disappearing randomly from playlists .

Sometimes duplicates (where two songs look the same, but there is an appended number in the title) are not exactly the same if you look carefully. For instance a double barline might be a final, or text has moved one space, or one has an END in it (which is invisible in song view).
Or someone may have sent the exact same song where its title (for some reason) already has the appended number. When this happens, the song is still imported.
Also when we updated our Jazz playlist from 1200 to 1350, some of the existing songs were corrected. Importing any of these (either yourself or by one of your band members who is emailing you songs) would result in an appended number.

You could tidy one device completely and the changes should sync to the other devices. (Make backups so you do not inadvertently lose any updated songs on different devices before doing this process.) And as you finalise each playlist, you could share it (perhaps to Files) so it acts as its own backup, while you sort out all your songs and playlists.

Your iCloud data might be corrupted for some reason. Instructions for clearing it is in Help>iCloud sync>Troubleshooting (with general information in Help>iCloud sync). Take the precaution of running backups on your devices for safety before (and perhaps after) doing this.