You can now include checklists from cards when calling t.card() from the Power-Up Client Library. To do this, pass “checklists” as a parameter, or use “all”. For example:
t.card('id', 'checklists').then((data) => console.log(data));
The returned information includes the name of the checklist, its position, and an array of the checklist items. This is similar to the results from the Checklists API.
For more information on t.card(), see Accessing Trello Data.
Our official changelog will be updated shortly with this information.