OK. By sheer dumb luck, I think I have all of the old Logic instruments. I have Fifth Moon back anyway. I don't know what the name of the organ is that people are looking for but I've got one called Full Cathedral that seems promising. The Channel Strip Settings directory is 81 MB, I thought of just talking about Instrument but that's 47 MB so most of it anyway. Is it OK to share this somewhere? I don't feel like doing anything illegal but I'd like to help people get stuff back.
In case you want to check for yourself, here's my process. I don't know where Logic stores stuff by default, I told it to put things in a directory called library on my external drive, that's because I thought it would make a Logic subdir, but it didn't. So the path is:
Library/Application Support/Logic/Channel Strip Settings
In there are subdirs, I just copied Instrument and pasted it into:
~/Music/Audio Music Apps/Channel Strip settings
That had a subdir called Instrument but it was empty. So I just told it to replace. Now at the top of my library browser in Logic, above Bass, I have "user channel strip settings" with the old list of instruments, e.g. 05 keyboards, which has organs under it. Well whatever the number is, I didn't open Logic to check.
So you never know, you might already have all of these handy yourself. But if you don't, and we think it's OK, I can zip the Channel Strip Settings directory and put it up somewhere so you can grab it and paste it into the appropriate spot. Honestly it would be useful to have somebody check and write this up properly.
I don't know where the other stuff lives, e.g. bus, so I didn't paste it in, and I don't know how to check to see where it would end up, or how to fix it if it ends up in the wrong place for Logic to use it. But according to a video I saw about restoring this stuff from 11 to 12, there are also older versions of these, I think he mentioned Master settings, that were lost along with the instruments.
To be clear, I know they all go to the same path. But I don't know if everything would show up in User Channel Strips in the library, and if it did, if that would mess anything up in terms of using mastering settings within Logic, for example, as opposed to the instruments. I don't know where the rest of them are in Logic right now and I don't know what you're supposed to do with them. So I wouldn't be able to check and make sure everything's working properly.
Anyway, if somebody needs this stuff and we think it's OK, I'm happy to share. I think you can get the instruments and all back in one fell swoop, maybe barring sample-based things. I just checked and Full cathedral from Organs works at least.