The Event-ID's for 737 and 777 are diffrent in PMDG!
737:
#define EVT_OH_LIGHTS_TAXI (THIRD_PARTY_EVENT_ID_MIN + 117)
which reassembles to 69749
777:
#define EVT_OH_LIGHTS_TAXI (THIRD_PARTY_EVENT_ID_MIN + 121)
which reassembles to 69753
(found in the sdk in the FSX\PMDG Folder)
Looking into the 777 Header the Event 117 will map to EVT_OH_LIGHTS_WING
So you'll have to make diffrent scripts for the planes.
No Idea why they changed the Offsets and not just added at the end ....