I though Bolster did not work on augments - that is, it did not affect the stats they shared with players, but it turns out I was wrong.
I tested it on Preview - spent a million AD on getting one bolstering companion from epic to legendary, boosting the bolster from 13.5% to 14%.
My augment's Power went from 10.256 to 10277 - an increase of 21 points .. .which with 3x R15 bondings gave me an increase of 65 points.
So, there you have it. It works...it's just pretty much worthless.
Remember: This is a game...it is supposed to be fun...