I remember a translator cell from somewhere.
This book wasn't bad. It wasn't one of the best ones, but it was solidly paced and moved pretty well. I liked the idea of the Venber, however organically unlikely they were, and there was some mysterious talk about The Five or something that I was intrigued by, but that's not an unresolved plot thread I can be too unhappy about.
There's some interesting discussion on tvtropes about how exactly the Animorphs were still able to think and reason in really primitive forms, and basically the theory is that the mass in Zero-Space, which we know is still at least recognizable as the original form, somehow remote-controls the morph from there. So even if they're an ant, they're still using their human brain, just distracted by the ant's instincts in real space. If that makes sense.
So, therefore, even if it wasn't a translator "cell" and was a "chip" instead, Ax could still use it since he can still use his Andalite brain.
Of course, to me at least, this begs the question of why the Andalites aren't just using Zero Space as a huge organic or inorganic storage unit, programming medical equipment to draw from vast supplies of blood or medicine, programming weapons to draw from vast supplies of fuel or ammunition...but idk. I think about Animorphs way too much.