As I said before, 1:1 collabs are different than group collabs. 1:1 collabs means that you can pause to let someone else mentally translate, never mind that you can clarify communications and so forth. Kaleido group collabs don't give Clara that luxury.
Having Clara in the JP branch wasn't a bad idea on the face of it (before we knew about the politisperging). Being a non-JP JP-language vtuber lets her stand out from other talents, gives her different stories to tell, different experiences to share and so forth over other JP streamers. It can also attract viewers who might be interested in something a bit "exotic", for want of a better word. Pity that Clara is politically brainrotted and does over ninety percent of her streams in English, which I imagine would be pretty frustrating for a JP viewer of Clara's.