If backdoored constants are easy enough to find that you are able to find them AND they are appropriate English phrases then the cipher itself is likely broken

If backdoored constants are easy enough to find that you are able to find them AND they are appropriate English phrases then the cipher itself is likely broken doubly so as the origional version of chacha had 2 key sizes 16-byte and 32-byte and each used the applicable constant, so in this case you would have had to have found 2 matching back doored constants. That being said you aren't crazy this is what the nsa was accused of doing with elliptical curves though they had started with inexplicable random seeds.