I created your environment in my machine. When I started the script, I got
./data.sh: bingo!: no such file or directory
It's saying "the file bingo! does not exist". Lets see what happened. When you use the input redirector "<" you are saying to the shell read the contents of the file, in this case, "`cat value.txt`". Then, first the shell executes the redirection specified by the grave signals, substituting the expression by the resulting content. So, now you have a command like
./process.sh < bingo!
This file doesn't exist. Besides you want to pass the file contents as a parameter to the process.sh. You need to remove the redirector "<". So, your command, after the substitution will be
I hope it helps.