They're Japanese patents, so maybe they're already circulating in Japanese media and haven't been translated yet.
Alternatively, maybe the Japanese Patent Office requires you to follow some bureaucratic process to get a copy: like you have to be a lawyer and it takes 4-6 weeks to get your reply. I don't know, but Japan just finally got rid of its last laws requiring floppy disks for certain processes a few years back, so it's not out of the realm of possibility
I'm sure we'll hear the details soon.
X2go is the successor to NX and works well IMO, though I've never tried Rustdesk to compare.