I’ve found that the text styles aren't mirrored. That is, if you update the styles in the typography page of your design library, (change font, confirm changes in sketch, then push the changes to the craft library) you CANNOT then sync any artboards that are using those styles, they wont update. You have to manually update all the text on your artboard by clicking on the styles one by one in the craft panel. This then introduces a new problem, you end up with duplicate styles inside of Sketch. Nuts.
I found the Brand.ai was much better in this department and succesfully synced by text styles as well.