The Mirror of Twilight does not appear in Breath of the Wild.This isn't rocket science, if it is following current canon the presence of theand references to those events place it in that timeline.Twilight mirror
However, Princess Zelda does indeed appear to reference the events of Twilight Princess while she's going over the history of the Master Sword, apparently omitting events from other timelines. While I assume Breath of the Wild takes place in the Child timeline long after Twilight Princess for this reason alone, you can read my post above for possible problems with this evidence.