I know a lot of people from Grumbach including one Volles who played trombone with my daughter and football with my son.
I can get access to the official register books. I need to know at least one, better two or three certain dates to start a research if you`re interested in birth, marriage and death dates. They include of course no baptism or confirmation dates if you`re looking for this kind of information.
I also would like to recommend to you the
Institute for Palatine History and Folklife Studies in Kaiserslautern who are keeping some data about Grumbach in their files despite it being a few meters north of the river Glan that is supposed to be the border of the Palatinate.
Their database
https://migration.pfalzgeschichte.de/ isn`t yet complete but maybe you can find something there. The late director Roland Paul spent a lot of his time in Brasil, I hope his successors have kept a lot of the knowledge he could gather there.
Greetings from
Rainer