I think alot of the reason that there seems to be many posts about problems on the Lag II is that there are alot more of them out there due to their popularity as a rep car etc.
The Laguna II phase I does seem to have alot of common faults. Your Laguna being a Phase II should have had most of the Lag II common faults ironed out, so should be pretty good tbh.
I had a few issues with my Laguna II that I had but despite that I still loved it to bits (maybe not at the time of the problems) and do miss it even now.
I would stop worrying about it, enjoy the car and relax in the comfort of being able to lean on this forum for help incase of troubles.