How did you come to build this collection? They're all in different sections...
Each nibble (four bits) in those five bytes is a row or column of the board, top to bottom then left to right, encoded as:
0: 0
1: 1
2: 1 1
3: 1 1 1
4: 1 2
5: 1 3
6: 2
7: 2 1
8: 2 2
9: 3
a: 3 1
b: 4
c: 5
If you concatenate all the clues_*.txt files, in order, to a single file, you can search through it to get the number of a pattern using standard tools, e.g. $ grep -n $(echo c222c c222c | xxd -ps -r | base64) clues.txt
452085:wiLMIiw=
Which is the nonogram at https://pixelogic.app/every-5x5-nonogram#452085.I have uploaded and archived a copy of that combined clues.txt file at https://web.archive.org/web/20250604215009id_/https://litter..., to help anyone else who would like to explore this without having to download those tens of thousands of files.