... but is there an erratta for Battlefleet Koronus? Or, is there set to be one?

If there isn't one in the support section, there isn't one yet. We won't know when one is coming out until it's released (given those that help make it are usually under NDA).

Not that I know but here is a Link to a post that has some answers from Sam on some of the FAQs that I have seen crop up.