"Crow-shechka" is fun. I love making language mutants. Lapushka is good also, but I think my US readers will be able to handle only one diminutive.

Here is her response when he "names" her (she speaks no Russian):

"He might be calling me his bald-headed baby buzzard, and I would still be charmed."

As long as it works for him, it's all good. They'll wind up marrying at some point, so intimate is fine.