Based on the information provided, the best option that describes what happened is:
Option #3: Percy made a mistake and did not match corresponding points correctly. She should have translated \( \triangle GHI \) along a vector that takes point \( G \) to point \( L \) when creating \( \triangle G'H'I' \).
This option makes sense because for the two triangles to be congruent, they need to be properly aligned in corresponding positions. Translating from \( G \) to \( J \) rather than \( L \) would prevent the triangles from overlapping, indicating that they have not been positioned correctly.