Rose definitely DOES know about the security spell and is perfectly capable of informing Trace that it zapped a couple of intruders who have already provided a couple of fresh eggs for the next morning's breakfast.
Whether she chooses to so inform him...
Non-evil Trace (assuming he's informed) will almost certainly desire to change them back. But he may not know how. Reni may or may not know how. For that matter it may take a mage of Lady Nora's power-level, so Trace and Reni may not even be theoretically capable of it.
For that matter, we don't know what long-term plans might be built into the spell. Maybe, unless there's some intervention to the contrary, it holds them for a week then transforms them back and teleports them into a treetop five miles away.