Ah, OK.

So it looks like as everything is ok. US still has stored the LX PNR, as once an LX flight was booked in this file, that's normal. But it's cancelled as you wrote, so OK.

The segment showing on SV.com between LGA and JFK ist completly legal. You arrive at LGA and depart from JFK. There in between, a 'flight coupon' with the indication 'ARNK' with the meaning "arrival unknown" is issued. Thats according IATA rules, every time if you arrive at an airport and depart from another. The airline departing from JFK cannot control, how you will be arriving at JFK...

So, if the data from Saudia.com is identical with your flights on US.com, then you're fine and no worries about your travel!

But keep having an eye online and check regularily the flight status on US.com and on each individual airline flown, as you never know if changes happen...! US usually won't contact you if any changes happen...

Or sign up for http://airlineroute.net/, then you're informed abour schedule changes and modifications...