I am not Lutheran but in the Catholic religion there is a sacrament of Confirmation and also of Communion.
Confirmation is when one confirms membership into the catholic Church. When I was a kid this sacrament was performed around age 10. Today usually 13 (eigth grade) or after.
Communion is a sacrament celebrating the first time one takes bread and wine during mass.
those "Communikantenverzeichnisse", as I have learnt so far, are lists about
all people in a Kirchspiel, who were allowed to receive Holy Communication.
I was aware of Communion (age 10) as a sacrament in the Catholic religion,
celebrating the first time one takes brad and wine during the mass as you've
mentioned, but wondered what it had to do with the Lutheran religion,
because this part is called "Confirmation" (age 14).