Hello, beeblebrox,
I've been looking into this issue of extracting annotations from Personal Documents in the Kindle app in Android devices, and I'm interested in this information you got about the sqlite db.
In the mbp reader perl script you mention, it is possible to set a parameter that divides that location by 150, thus giving the Kindle location position (with an offset of 1). Can you try that with the number you got from the sqlite db? (My phone is not rooted, and I don't intend to do so, so I don't have access to that file here)
Just for the record, and slightly unrelated to your question, I found a way of getting the mbp file without encryption by downgrading the app to the version 3.6.0.87. I'm thinking about making a python wrapper script to the mbp reader perl script to try to convert the notes into a format that is compatible with the My Clippings.txt, so that it can be uploaded to those services such as ClippingsConverter. Let's see
Cheers!