According to preliminary research, yes it is true. But apparently there are a host of CK errors and the CK might require an update. Not 100% clear on that one yet, just know that we were warned not to use the CK with these masses of new errors.
Apparently there was a new sub record added. So, I would advise waiting for the CK to be updated.
Yes, the main TES4 header that all files share in common got a new INCC subrecord that the CK is not aware of right now. The TES4 header record is not something to take lightly and changes there are usually pretty important.