Hi @Richard_at_Qantas ,
With reaction event I think you only check email open and click and not exactly which link/button was clicked. Alternately you can try creating a segment with following schema fields value and use that in the journey. I have used these in CJA for tracking email links clicked, I think it should work for segments as well.
AJO Email Tracking Experience Event Schema._experience.customerJourneyManagement.messageInteraction.label
(This filed provides text of link clicked)
AJO Email Tracking Experience Event Schema._experience.customerJourneyManagement.messageInteraction.interactionType
You can also include message execution id to make it specific for the message.