This sounds about right; they definitely released earlier versions of MKII that had yet to be tweaked. Bosses were notoriously difficult, and the AI was even worse than the final product (if you can believe that, lol). That's actually a topic I plan to do a video on in the near future!
I remember playing my first game of MKII in a local pizza shop. I was enamored by the cabinet and attract screen, and insisted my mom give me some quarters while we waited! I don't remember who I ended up picking, but I DO absolutely remember facing Jax first, getting wrecked, and being tossed into the acid of the Dead Pool. That image and sequence left a huge impression on my then-6-year-old mind. From that day on, I've been a die-hard MK fan for life!