The CIA's legitimacy was undermined decades ago. Just look at their history of overthrowing democracies, or what happened in, say, Iran.

They do have a category on Russia, though: https://wikileaks.org/wiki/Category:Russia

IIRC, they don't have any staff fluent in Russian, though, and they pointed to other whistle-blowing operations as more able to operate there.

Russia doesn't need to collude with them, nor does any other party. They just need to leak to them. If you read what Assange wrote about how wikileaks works to raise the cost of conspiracies, you'll see that it actually doesn't matter who is using them, only whether or not the material is true.