It took a while, but Spark now has a dedicated update service, that can be configured to routinely update a gaming account in the background. So far, the feature has been working without a hitch, though more testing is needed, and notifications need to be implemented. I’m also not convinced that the widget is updating as expected.
While monitoring the update service, I noticed something unusual – specifically, that the only time the system re-authenticates is when the Friends list needs to be updated. I tested by removing Friend update from the background task, and saw updates breeze through from that point on.
I'm a programmer with too much interest in too many programming languages, and not enough time.