Thanks for updating the profile with the current death date. A previous version of GMOL showed the 1785 death date which is likely why same was shown on the Geni profile. It appears GMOL has updated the death date year to 1786. Not sure why, but presumably they had a good reason.
Regarding the Cristina (Justina) Von Dycken name designation, i would likely not have changed that without consulting other profile managers since i have found over the years that historically the Justina and Cristina names are often used interchangeably. Justina may be the name that has been used over the years by some of the descendants.