Hello and thank you for your answers,
Everything (including legacy logic 10 sounds, intruments, loops etc..) from the sound Library in Logic Pro menu has been downloaded, uppgraded (when it had to) and installed (see the whole "Manage pack" window and " Legacy logic 10 sounds" screenshots attached as an exemple. All available packs are updated and installed according to "Manage Packs", I checked each of them).
Unfortunately, still no legacy/ancient stuff showing up hitting Y or clicking the library icon at the top left of the UI.
Part of the downloads/packsupgrades have been made AFTER that I moved Logic Pro libraries( The new Logic Pro Library.bundle file) from its initial location to an external ssd.
Maybe the dowloads/upgrades made after this move didn't change anything to the ssd's Logic Pro Library.bundle file, although, in Logic Pro 12, it's path is correctly saved and showing up in Libray settings which indicates the new Logic Pro Sound library location. Maybe those packs downloads/upgraded are saved somewhere else on my main drive.
Unfortunately, I didn't keep track of the initial Logic Pro Sound library location path...
In case that you didn't move your Logic Pro sound library to an external drive, would you please send a screenshot of its "by default' location path ? So that I can check this ? ( Google searching, I could'nt find this info). Thank you in advance in this case !!
Next step would be to uninstall Logic pro 12 and reinstall it. But.... I have lots of third party stuff installed ( Native instruments, Toontrack, celemony, Spectrasonics etc) and as I never did it, had to do it, I'm afraid that it could generate unexpected big mess/ new or other difficulties.
Cheers from France !

