DaMoshe, The certificate provided on their website is signed by the same person who signed the stickers. The stickers are merely a marketing scam to get people to purchase the product from a frum store instead of CVS or Walmart.
That being said, there are different standards in Kashrus, and not all Ricolas meet everyone’s standards. I have spoken to other agencies in Europe who have visited the plant and were not happy with the Kashrus standards there.
Many American hashgochos do not accept all Ricolas, only specific flavors. A list can be found on the cRc Chicgao’s website.