I worked in a place with a lot of people who worked in the Engineering dept. These folks designed, revised, worked with the people on the shop floor to resolve problems, etc. None of these folks were "Engineers". They were all referred to as "Engineers". It's just a common term for people who do jobs like that.
We also designed and manufactured a couple of life-critical gadgets - things which might result in a death if they failed. Those drawings had to be signed and stamped by one of our two certified Engineers. But we would have been find into oblivion, I guess, 'cause we referred to just about everyone on that floor as an Engineer.