For the 6,000,000,000,000 million billion time, there could be a weeks delay in sending the acars messages they will still show aircraft system time taken from the aircraft reference clock as indicated at the time of the event. I don't know how to make that any clearer
Safety Concerns, you are correct in that there is no guarantee on the delivery time for an individual ACARS message, however I understand the Satellite Ground Earth Stations have an Service Level Agreement with SITA which requires the message delivery time is less than 60 seconds in 99.? % of the time (can't recall the number of 9's). I understand there was no significant delay in transmission in this case.