I also attended the event and asked if anyone on Scadrial was cosmere aware pre-Lord Ruler.
He said yes (including Leras and Ati).
After looking a bit more into this I found that someone else was also thinking along the same lines and got a more detailed confirmation from Brandon: https://www.reddit.com/r/Cosmere/comments/5b66wg/no_spoilers_kwaan_might_have_understood_realmatic/ and https://www.reddit.com/r/Cosmere/comments/5b66wg/no_spoilers_kwaan_might_have_understood_realmatic/d9njbqq/ Kwaan was cosmere-aware and trees can think.
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