The presented ciphers make for an interesting study for folks who are into this sort of thing. For those who are not, well, there's going to be a lot that they have no reason to consider. For one thing, we already know that the ciphers have been altered, or that they maintain at least one additional element beyond simple substitution, if in fact they contain any meaningful clear text at all. This is why you can't rely on any statistical summation that has drawn its conclusion by way of analysis of the entire code as this procedure has already been proven to be ineffective before the process is ever began.
My point, once again, is simply this; unless someone is already privileged to at least the design of the code then they can run all the statistical analysis they desire to no avail. Per example, there are 19 four digit codes in C1 and it could just as easily be that those codes are the only codes with meaning, the rest just being completely meaningless and simply included to add confusion? We already know that there exist, as masterpoe points out, intentional strings of codes that present additional element. So any type of statistical analysis that utilizes the entire code is an effort already defeated. The down side to this fact, is that this knowledge then allows anyone to apply only those codes they chose to apply, and of course, this can result in an endless stream of the same type of manufactured solutions that have become all too common in this mystery.
In other words, once you know how the code was designed then you can go to work writing programs in search of specifics, but if don't know how that code was designed then you can only write programs that search for specific clues to that design, which means the search criteria is subject only to "human expectations and suspicions" within this otherwise complete unknown.
Time and science have already established that in its presented entirety that C1 cannot contain a grammatically correct English translation by way of simple substitution/book cipher, etc. We already know this for a fact so why keep trying?