I disagree with the latter part of your reconstruction. It goes more like this:
""The actual reconstruction of events is the following: Sylvanas torches the tree and Elune, called there by the night elves' prayers ends up soothing them and then sending them to Ardenweald, since she's heard on the grapevine her sister needs a helping hand. She then shrugs and goes to read her newspaper. She later finds out that all those souls are actually going to turbo hell. What a bother. Feeling awkward about this she lets Tyrande act out for a bit until the fight with Sylvanas where the former intends to sacrifice herself to ensure the death of the latter, overloading herself, but Elune doesn't want her High Priestess to die so she pulls the plug on her abilities."
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Instead of claiming the souls for herself as wisps, she let them go into the Shadowlands, intending for them to help Ardenweald in the drought... but then she finds out they were sent into the Maw instead, thus thinking she's condemned them.
Not that hard to follow really.