"weird" letters

Had to guess on a lot of spaces at the end, but it might have just been me and I got it right on the first try. Still a really nice puzzle! Thanks!

I got several answers, all invalid, I gave up.

Icant get the right solution.

I got it on the first go. The 3 in row 1 starts in column 1. The 3 in row 10 starts in column 19.

I guessed right! fill in r5c4, r4c14, r4c22.