There are both Males and Females in the city.
For me, the question was: Are there any female Engineers, like the ones on LV23? The sacrificial Engineers.
The confusion between the so called "types" of Engineers is the issue.
My point is that the Engineers 223 do NOT have Females. Nor Males for that matter. The have no sexual orientation as they have no need to reproduce.
They were an organic creation made by the Elders for various reasons. To link with civilisations, Eradicate planets deemed not worthy by the Elders and every few thousand years, when a planet is ready they give the ultimate sacrifice.(Prometheus intro)
Now they were made that size, possible clones made as the ultimate designer baby.
We see them and assume Male. Partly due to the muscle structure. But in fact are made to be strong.
They look young as they were "born" that size. The Elders gave them several ways to breath so can survive on any planet.
So the Engineers 223 - dont have females IMO
The Engineers 223 - dont have males, they needed to be strong so are built that way but have no need to reproduce.
So that is my take on the Female Engineer topic. Just a theory really.