Yes, earned boxes before the update can drop the new plans if you didn‘t open them once before the update.
The drop chances are pretty low though. Got 7 plans out of 120 boxes, where three where exactly the same purple plan…

The drop rate for the new High Elf, Ancient structural plans is significantly lower than the last couple rounds of Solstice plan collections from similar daily reward sources. My first 184 Summerset Daily Recompense boxes resulted in only one furnishing plan.After that, the rate was a little better, but not by much.

Such low drop rates are disheartening and frustrating for players who are seeking the new plans.

At least we know the source for the structural plans. We still don't know exactly the sources for two of the U50 Antiquity furnishings, and the new Breton plans seem to be extremely scarce.

Aylish wrote: »

They are dropping from Geyser reward coffers as well? Patch notes state, they only drop from WB and delve dailies…

Yes, I specifically tested it on the PTS because Geysers were omitted from the PTS Patch Notes. When U50 went live, I also opened the Geyser coffers separately to track the drop rates for each type.While they all share the same name, there is a subtle icon to denote which boxes came from what source.



Since the Geyser dailies are only unlocked by doing a significant part of the zone story, I presume that a lot of players only have it unlocked on a character to two, if any. I was likely omitted to save on some FOMO, when the rates for dropping plans were so low.