Actually the 1900 census shows an Adam Vosbury as born in Aug 1868 and Luisa born in Jan 1872. I could not find this Adam with anything similar to Vosberg in any other census. Also the children's names, ages and birth order are rather consistent with the children I found for Adolf and Louisa in the other census records. I realize this still presents a problem since his first name is wrong and he was born in the wrong month. To clear it up what were Adolf and Louisa' children's names and any birth dates you know of? BTW it's not uncommon for children to be listed in one census by their first names and in another by their middle names (not all at the same time of course).
One clue that helps makes the case for the 1900 census finding is the fact that when Adolf Vosberg (born March 7, 1869 and arrived in Baltimore June 27, 1886) was naturalized in 1902 he was living in Duquesne, PA. In the 1900 census listing of Adam and Luisa they were living in Duquesne, PA.
It's often easier for people to say they were born in this or that city rather than explaining they were born in a small town nearby. If Adolf was born in Frankfort itself there were probably several churches he could have been baptized at. If he was actually born near Frankfort there are probably dozens of churches he could have been baptized at.