It mostly legalizes European trainsets with minor adjustments, though Japanese sets would need significant reworking since they follow yet another standard. But this is important, because an FRA-compliant vehicle at 220MPH basically does not exist, and those have become legal if in their own exclusive right-of-way; and alternative compliance trainsets can now operate with regular American freight trains below 125MPH, which is basically the entirety of the network today anyways.