[just your first question] I don't think it necessarily implies an internal language, as crows, not being mammals, have a different brain structure. Specificall

[just your first question] I don't think it necessarily implies an internal language, as crows, not being mammals, have a different brain structure. Specifically, they lack a neocortex. They instead have an independently evolved higher brain structure called a hyperpallium. Corvids (including crows) have the largest of these, amongst birds. Kinda, the apes of the bird world. So it's possible the relevant processing centers are not separate in them, as they are in mammals, and do not need an internal language to bridge them. Therefore, while it's possible they do have the same problem and solution as us, this experiment doesn't imply it. I wonder if there's a way to test which it is? e.g. something analogous the interfering with this internal language in humans that a commentor mentioned.