If it's anything like on my system, the missing files are a product of the game files quietly getting moved over to the infamous MutableBackup folder during that period when you try to open the launcher/Tweaker and nothing happens. At this point the game needs to redownload everything to the proper game folder, on top of now having the dead files in MutableBackup... at which point you pretty much need to do a full sweep to clean up the trash and do a fresh install.
As for where that's gotten me, the distro for the installer is completely tapped out from presumably all the other people having launch issues today. I'm lucky to get more than 10Mb/s on the download consistently, with regular timeouts on the download. Honestly it's about as bad as PC launch day was, lol.