Oh, you were very busy as a kid.
I inserted Konfirmation and Firmung into both Google translate and Deepl but both translated to confirmation. It seems there is really just the one word for both. And it seems the same way in Spanish: confirmación.
So I did the same with latin: and behold!
firmare = to strengthen
confirmare = to confirm (duh)
"confirm implies the removing of doubts by an authoritative statement or indisputable fact."
"to prove that a believe or an opinion that was previously not completely certain is true" (Cambridge Dictionary)
So there is a slight difference in the origin of the words, but in use they describe almost the same ceremony.
Now I am thinking of "firme el documento". I was confused that it means to sign. But now, when I think about it, it makes more sense, because one could see it as a strenghening of the document, when it is signed. Sometimes there are words that have seemingly gone far from their original meaning.
Something else: I had a massage today. It was very nice and relaxing.