This one perhaps deserves more attention.
The goldsmith's quest, F'lhaminn's Flower, has the following gossip from the greatloam growery:
So the Botanists suspect an assassination order on Nielle. It is of course speculation on their part, but possibly an informed one?
The cutscenes don't put a date on Nielle's passing, but at the very least measure it in years.
Chrysaliswiki has thankfully kept a record of the rest of the non-cutscene text with this juicy bit:
EDIT:
WE HAVE A DATE FOR UL'DAH'S ECHOS!
From
She Walks in Beauty:
If we combine this with the assumption that strife concerned involved the assassination of Nielle, the breaking of Heartstrike (in which the Ossuary had invested) and the dismissal of Nielle's father as guildmaster, we could assume that the echoed scenes indeed align with the lead-up to the Battle of Silvertear Skies.