The analytics plugin adds the entire basket as a transaction. It then adds the individual items of that basket as products purchase (there's 2 parts to analytics, products and transactions). Each purchase should record a transaction assuming the Order ID isn't a duplicate.
In addition to this analytics is very slow in reporting commissions (is a free service after all) and can take 24-48 hours to show a purchase, it's also possible if they have any down time during this delay you could lose a transaction record all together. I would not use it for accurate financial representation, but as a good estimate.
I'll review API further to see if they've made any changes that would require any changes to our usage.