The mother of the 5th Phantom died in childbirth. If this isn't a contradiction, the 4th remarried and it wasn't Giovanna and likely not Katarina Ulrikasdotter van Wallenbach.

At this stage she is unnamed, with blonde hair and obviously had a close enough relationship with the 5th that he would go back to Bangalla to be with her as she passed. She lived past the 4th Phantoms life.

In Bastei stories his wife did not die during childbirth.