This doesn't violate the Constitution because the person granting the titles is not a foreign ruler. And the title "czar" might be considered a title of ignobility rather than one of nobility.
“No title of nobility shall be granted by the United States”
That seems to cover the grantor other than foreign states or nobility. It seems to say, "No title of nobility may be granted by the United STATes. Perhaps the claim that the term CZAR is not being applied as nobility, however if we applied the term 'Prince', or 'Princess' or 'Emporor' it seems to take on a meaning of the word and is not just a euphemism.
If we look at the First and Second Amendment originalists seem to want to believe the words written. The mechanism to change the constitution used to be the adoption of a constitutional amendment, a constitutional convention, and now, the most popular, by judicial decree. Now, Presidential decree seems to be being applied.