Amazing speed of response and how appropriate that it's your post 101. I'm impressed.
I've tried to work out what you've done with some but not complete success. There seem to be two (or three?) anchored objects inside each other but I'm finding it hard to select the different elements. I've not worked how you mirror the arrow and change colour.
Anyhow, I played around a bit and got a bit further. The arrow now changes position too. I changed the anchor reference point for the inner reflected object, set the text frame to align to gutter and added equal padding on both sides of the text element. I've not quite got everything working, though, as the right-hand (green) arrow is a little larger now (a separate element?). Anyway, try out this IDML file.
test2_reflective_bullets.idml
I'm wondering, of course, how easy this is to implement in practice. Does this complex assembly of sub-elements have to be hand-constructed for each item?
Thanks again!