You could compare the factory routes with a genuine model but other than that its very difficult, im not even sure it will definitely be Alder because the earlier MIJ models were'nt except for the sunburst models.
To be honest i would not be concerned because if anyone was to go to the trouble of a counterfeit they would do it for the big money and try and sell it as a vintage model.
But what i would do is look in the cavitys to see if it is solid wood. You may need to gouge a bit of the wood to check, if it was made of plywood or MDF you would be on grounds for a refund.
