The plaque reads, in English: There is *a* SAYING.  Those who *be*

IMPRISONED must sound their way through their predicament lest they *see*

their only option is to GIVE UP.

A19
B9
C7


So caps letters represent something.   Theoretically positions of the various notes in there.  Issue is in order to have a note for every letter, there have to be a minimum of 25 octaves there.   More than that if you want to get into the fact that the middle C on an organ is what is considered a part of the "0" octave.     The C itself is the 0.   Which means there have to be octaves to the left of this.    So 25 octaves minimum to the right... that's 200 keys minimum to the right of the center C.   Which means that this theory is probably wrong.   If we go with only the first letter mattering, then we assume that there are 19 octaves, or 152 keys.     If we go with the last letter mattering, then we have only 16 octaves, which puts us at 118 keys to the right of the center C.

S  A Y  I N  G
19 1 25 9 14 7

I M  P  R  I S  O  N  E D
9 13 16 18 9 19 15 14 5 4

G I V  E  U  P
7 9 22 5  21 16