In an effort to get the objects further into Wally's head, I'm going to try making the object a focus of any games or training we do.
The games aren't anything fancy. This afternoon, I just moved the bone around on the floor and while he was trying to get it, I kept saying "hueso! hueso!" while he was focused on it and trying his hardest to grab it. When he does get it, of course he get a reward. Then we do it again.
I also would hide the bone behind my back and ask him "Donde está hueso?" to get all wound up and trying to find it. Once he's looking everywhere (and away from me) I'll subtle hold it out and repeat the question. He then sees it and comes over to grab it and get the reward. A variation of this is for me to throw the bone up on the bed while he's still distracted by the reward. I then ask him "Donde está hueso?"again and he starts looking around. I only keep repeating to keep him eager.
I probably shouldn't have done this, but I also threw in a new spanish word "obtengas" form of the verb meaning "to get". I do want to turn "get it" to a spanish cue too, but I might not should have done it while also trying to focus on the bone. Anyway, I worked it with throwing the bone and saying "obtengas hueso" and rewarding when he gets the bone and brings it back to me. (I know that might not be exactly right, but it works for him - teaching him one word for the object is hard enough to get even more complex with it!)
Continuing to work this with him will at the least immerse him in the object's name and shape. From there, I am hoping he will be able to make the connection between the name and object.