Celebration is a "good" idea, but horribly pricy for what they actually do.
Having a celebration using some confettis and effects on the stream is a great idea altogether, although, you're missing one thing :
That can be done. FOR FREE. Kappagen and Emote Walls already exist, so people already have access to a "free celebration" already.
Moreover, one "small" celebration is the price of a monthly sub. Somebody used it on stream and their first reaction was "I instantly regret it.", making me wanting to remove the function altogether from the channel. I want to make people smile, not have them sad at an overpriced function.
Also, people have to "pay" to get it, they cannot even use bits to do so. PLUS, added to that, 50/50 cut on top of this makes this even worse as an option, because if you get a sub, on most if not all streamers who have kappagen on: you can literally have a flowery emote celebration with any sub, follow, donation, you name it... Making this entire "feature" pointless.
While it came from a nice viewpoint, this is an obvious cashgrab unfortunately, and people are ALREADY not liking it. I don't even want it anymore while I like to have things to interact with the channel with!
That said, it is not completely unsalvageable.
A way you could change it is integrate it with the Channel Point system. Have them do a big celebration when a HUGE point redemption is redeemed!
Or integrate them into the Subs/Cheers. Not as a solo thing. Give more value to what you currently have, as those options aren't unfortunately the best to support the streamers at the same time as most people who want to support a streamer will either sub (for emotes and ads)/cheer (because they have ads for bits)/donate (because the cut is way better for the streamer overall).
Give more value to the things you have, or give enough value to the feature you're going to involve in the stream. This feature has none of that, and it is hard to "celebrate" when both sides feel this ripped off. I'd rather have someone sub to me at that price and use my emotes everywhere for a month or remove all ads (which are very much a problem as well at the moment) than to have them have confettis for 5 seconds that I cannot even see.
More interactive things are needed on Twitch, so you're not exactly offcourse, but this was a shot in the dark that landed right in the head of the community here.