Just to confirm we should expect data at a promotedtweet level to roll-up and match data for the joined lineitems at the lineitem stats level correct?
This is relevant, from our Analytics Best Practices:
Do request data (ideally) at the line_items and promoted_tweets level, as you can always aggregate and roll these metrics up to get totals across the entire ads entity hierarchy (i.e. for the campaign, funding instrument or account levels).
So in short, yes!