Indeed. And getting the the portraits back is a little more involved. If the achievement progress was also lost, you’d have to use allyourbasearebelongtous on every mission. To avoid all that, I’d recommend occasionally backing your progress up. Here’s a guide for that too.
Yeah, just start any mission and paste it into the chat.
Hopefully someday they either make those files less damageable, or they move the progress storage to Battlenet.