From what I remember Vei was notable in her absence for Mouse's big 5 year anniversary too. Vei's been checked out for a while so it could mean something, but it might not also. Vshojo Unity has kind of dwindled since the early days of the org, with big collabs petering out between them in favour of specific friend groups. For example Mouse and Nyan regularly collab, Zentreya and Haruka, etc, and Veibae was a later addition compared to the likes of Silvervale who is old friends with Mouse/Melody.
In terms of Nazuna, Mouse had made efforts to collab a couple times, but in comparison to Kson she's notably isolated in the company. I'd put that down to her being Japanese-only, the language barrier really is pretty rough for the impromptu unofficial collabs Vshojo favours these days. Arranging everything to be like Mouse's Haachama interview with a dedicated translator is pretty high effort. Management could try to help, but the thing is that Vshojo's atypical setup means that a talent has to specifically ask for help if they want it. They don't have someone hanging over them at all times with advice and directions like you'd see in Holos, and I pity whoever has to interpret Nazuna's latest manic episodes if she ever does ask for help.
As an aside, Silver's latest stream has been a goldmine for based quotes:
ㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤ
