Holiday troops don’t get announced as released, they end up in chests automatically after 4-5 weeks. It’s in the official patch notes:
Jeto, I’m sure it’s not your fault, but this isn’t a solution, it’s adding insult to injury. Some players wasted thousands of event keys chasing a troop that, by all official communication, should have been around. We have no way to know when your loot boxes don’t contain what they promise, due to configuration errors, we have to trust that we don’t get cheated out of rewards. Please bounce this back to whoever is responsible for this mess and kindly ask them to come up with a proper compensation scheme.