The whole point of Ultra Magnus’ character development is to move forward from that “two expressions” point. Every single panel given here happen after he confided about himself.
i agree with you, but not entirely, while he definitely became more expressive afterwards he didn’t have only “two expressions” i included only expression from later because he is more expressive, which i think is also due to a different artist (everyone became more expressive) but here are a few pre-talk-with-swerve expressions:
Naama's blog 