It looks real to me
I can't see a bricks and mortar shop selling a fake, then accepting that fake back for a warranty service. Shipping it to Shimano which inspects and repairs before shipping back to the retailer...Nah, way to many people involved....If it was just the retail bricks and mortar shop that did the warranty service, there might be a very slight chance of it being a fake, but even then the chances are very, very slight.
I do not know how many thread line reels I own. Seriously, I do not know. My last count a few years ago was 57 rods, but I have no idea how many reels. Like wise, I really do not know how many Shimano reels I own....I am getting old and turning in to an old tackle rat
I have never seen a thread line reel that does not have counter weights. A lot of the cheaper ones simply make the body thicker where the extra weight is needed. But which ever way you look at it, a counter weight is needed to off set the weight of the bail arm assembly. Especially when using multiple ball race bearings which will "echo" the affect of any off weight discrepancy.
The "plastic" gear cog is probably nylon. The only load bearing parts of a spool assembly is, of course, the drag and the bail arm roller. I don't know what this "plastic" cog is for. At a guess I would say a "clicker" for the drag control or maybe part of the "anti-reverse". Whatever it is for, it is not a load bearing gear cog and even being made of nylon is probably an over-kill...If I saw this gear cog made of an alloy, I would think 'cheap and old school'.
itsaboat mate...Life is just a boat and then ya marry one !