You have a keen eye lol. Thats actually done on purpose. The box art for wolf link had a slightly different logo. The O in "Legend of" has a diamond in it in the newer amiibo where the wolf link didnt have that. And like you noticed it is slightly smaller on the wolf link amiibo. Personally I wanted to match the amiibo box art so I made the logos different to match the different logos used on the official box art. But you can edit it if you like it better so they all match.
You are absolutely right! I never noticed that diamond in the 'O'.. Looks like my eye isn't so keen afterall haha. Carry on then