It’s generally assumed that you’ll be printing out the pieces, & can thus flip them over easily. So you’ll have to re-trace the pattern piece from the draft for each additional copy you want in the layout, & if you need it mirrored, you’ll have to use the mirror tool in the draft before tracing it.
That’s not to say that there aren’t plans to eventually implement the capabilities which you sought, they’ve just taken a back burner since there is a relatively easy work-around.
This post: How to mirror a part in detail mode? - #2 by AVI may help you get the mirror function figured out. Note that it was made back when the mirror function was called “flip”, but it’s the same tool.
I hope that answers your question & helps!
