Can't Figure Out Why Trigger is Not Firing

On your layers, the "when timeline starts" trigger is changing the state of the Marker on the base layer, not the Marker on the layer itself. Because every narration button is called "Marker", the two look identical in the trigger's object list, so it's an easy one to pick wrongly. On "Land Acknowledgement - Explanation", both the Narration On and the Else (Narration Off) parts point at the base layer's button. On "Explanation 2", the Narration On part points at the base layer but the Else points at the layer's own button. The three layers on Centralized Services have the same issue. The fix was 2 things; 

1. Rename each button in the timeline so they're unique, e.g. "Narration Btn Base", "Narration Btn Expl 1".
2. On each layer, delete the timeline-start trigger and rebuild it: Change state of 'this layer's button' to Narration On, when the timeline starts on 'this layer', if VoiceOver = True. Else, change it to Narration Off.

I changed a couple of other bits that weren't quite right too