A morganatic marriage is one in which the spouse doesn't share the titled person's title or style (although, in many cases, a lesser title has been granted to them), and the children have no rights of succession. However, it doesn't affect the title or style of the partner who was born royal.What exactly is the difference between an unequal and a morganatic marriage?
In the case of Carl Gustaf's sisters, who made unequal marriages, they themselves were stripped of the style of HRH.
The reason she was officially "Baron" is that legal gender changes in the UK are not recognized for the purpose of succession to hereditary peerages and other hereditary dignities, per the 2004 gender recognition law (if she had been legally recognized as a woman for all purposes, she could not have inherited the barony, given the discriminatory male-only succession rules of most of the British peerage). The College of Arms roll of peerages now states she also uses the female form of the title, but she has stated that she is fine with being called by the male form and, if I remember correctly, even prefers not to use the title at all.