So event currency tokens got changed into a different legacy bound token that can be used to buy event currency that goes into your currency tab, thus freeing up some inventory space. So for example, all of the old Gray Helix Components were changed into Gray Helix Tokens. These tokens are Legacy bound items that use inventory space. You can use the Gray Helix Token to buy the new Gray Helix Components that go into your currency tab, and you can use this currency to buy a Gray Helix Token. The currency isn't legacy wide, though, so if you have to buy tokens to transfer it between characters. Missions seem to reward tokens, not currency, so this adds an extra step before buying something. Weird implementation, would have been easier to make the currency legacy wide, like command tokens were.
This change seems to apply to all 4 events, Rakghoul Resurgence, Relics of the Gree, Bounty Contract Week and Dantooine's Pirate Incursion. The problem is, the old Completed Bounty Contracts din't get turned into Completed Contract Tokens. And without the tokens, you can't get the new Completed Bounty Contract currency that's actually used to buy stuff. All items on the vendors require the new Completed Bounty Contract currency and if you try to buy something while you have a stack of the old Completed Bounty Contract items in your inventory, it gives you an error saying you cannot afford that item.