I tried this: I replaced the damaged .itl file with a past one from Time Machine with most of what I had before adding a couple of new playlists and artists. It was not too onerous to add these back in. The worst problem was to add back in two large playlists, jazz instrumentals and jazz vocals, which had many songs and are very eclectic formed from many different albums and artists. I was able to retrieve earlier versions with most of what I had previously had that had now disappeared due to Apple's screw up of iCloud Music Library. I created a folder for each and exported all the songs from each playlist, and re-imported them into newly created JI and JV lists in the updated library. Basically, all this effort worked to restore all the playlists or partial playlists that I could remember I had had before it had been wiped out by Apple.
I then made the mistake of trying to sync this restored effort to my various devices. The original having been created on an iMac, I needed to create matches on 2 iPhones, an iPad and a MacBook Air. Whether I used USB cable connections or WiFi, none worked properly, everything is now more screwed up than ever, and I have multiple copies of playlist names, some with all (or apparently all) my songs, some with only a few, some with some other amount. E.g., 4 different Playlists called Beach Boys now appear on my iMac (and several but not all my other devices), one with 10 songs, one with 59 songs, and two with 61 songs!! Similar multiplications of playlists with varying numbers of song contents have now proliferated throughout my iMac version of ITunes and on each of my iOS devices and my MacBook.
I am so furious at Apple for causing this I dare not call them to see if they can fix it or I will start screaming at the tech for having wasted 3 days of my life trying to fix this disaster. BTW, I am running iTunes 12.3.2.35 and OSX 10.11.3 -- way past when this problem or something similar started over a year ago with no help from Apple in fixing it! Disgusting.