Aren't bolt throwers from the late republic list heavy artillery? Their range seems ok and I read somewhere that fortificatins enable me to deploy them closer to the enemy....

Hello! I'm new to FoG and I'm trying to decide which army to choose. Late Republican Romans are one of the options. I'm curious if you find it a good idea to field an army based on bolt throwers.... for a beginning with 400 pts I was thinking about sth like a FC, 4x4 superior legion infantry, 4 LH, ...