It's not at all that a properly spelled sticker gives assurance that it's not counterfeit... it's just that a misspelled sticker is such an obvious sign of a potential counterfeit that it's basically the #1 thing that any counterfeit/suspect items program teaches people to look for. Most people working on counterfeits don't speak English so it's very easy for these kinds of mistakes to slip through, and on the other hand they're rarely made by the genuine manufacturer which usually has a process to check for this kind of thing even if the engineering work is done in a non-English speaking country (most of all that the logos usually come from off-the-shelf art files from the marketing department, so no one's even typing the name to make a mistake).
Almost any corporate or institutional counterfeit or supply chain security program will explicitly teach you: if anything is misspelled or shows other obvious mistakes, hold the part as a suspected counterfeit. It's a pretty good quality indication.
So of course manufacturers do genuinely make spelling mistakes sometimes, but this context makes it a pretty embarrassing and serious thing to do. It's like your bank misspelling their name in an account notification: sure, in some extremely theoretical sense it doesn't mean anything, but in practice they're giving you exactly the signal that everyone tells you to check for to identify phishing, and it raises questions about their processes that they let it slip through.