The latest development here is that Sonya Savage, the Energy...

The latest development here is that Sonya Savage, the Energy Minister at the time of the Albertan government's decisions, will be required
to give evidence.

https://decisions.scc-csc.ca/scc-csc/scc-l-csc-a/en/item/20969/index.do

https://www.cbc.ca/news/canada/calgary/alberta-sonya-savage-coal-policies-supreme-court-appeal-1.7513083

Alberta was trying to have her excused from doing so, but has now lost that battle in Canada's highest court - ie the ruling that she must give evidence can't be appealed further.

Also, it seems the trial has been delayed a few weeks - it was meant to start on April 28, but the article I've linked says it starts on May 19.