Wagon 12 again :(

mfw I reached this

Ok now I'm missing wagon #7, 14, 15, 16 and 19.

that took me pretty long xD
*edit and yeah i noted your hidden messages wordsearch style.
And thank you for the " 3 3 3" section, helped a lot :)

so. i noted three 7digit codes (without #) i found along the way. Is that the right track to #13?

I have the list of 18 wagons which I repeatedly checked the number of passengers and did the math.
Wagon 5 is a bit ambiguous, but even just trying both cases, I'm confused on why I can't solve this. Is it a format issue? Am I missing some secret? Am I an idiot? Some advice?

I assume Wagon 19 has 0 people?

Forgot to add "=" at the end, spent an hour redrawing the whole picture, heh.

Funny thing, I solved this one a couple of times until I realized I had it backwards. Was going from D -> C instead of C -> D.

Key received. Thanks P-Chan!