My guess is that the algorithm doesn't differenciate between 'self-voting' and upvoting 'other' accounts. It matters how often and strong certain accounts are getting upvoted (and also how many different accounts are receiving upvotes).
The algorithm cannot know anyway if the upvoted accounts belong to the same user or not.
I didn't write the algorithm of Voting CSI, so I can only guess how it works. It could well be that it also checks how often these upvoted accounts upvote each other (if they are building a closed group which is mutually upvoting each other) and how diverse the upvotes are which they receive from other users (in this aspect @haejin beats you).
All in all it does a great job to detect selfish voting behaviour. YOU and @haejin fully deserve the low rating. :)