Hi hacker 
alert 
I’m not a user of your software but read the entire readme (tons of information/wow).
Any file can be used as a keyfile, and a secure keyfile generator is provided for convenience
If you use a normal file, can it be insecure ?
Most people will uses a document, picture etc. I guess the distribution of data might not be random in those and it would make them less secure. Like a password of low length and complexity.
Not only can you use multiple keyfiles, but you can also require the correct order of keyfiles to be present for a successful decryption to occur.
My guess here is taht if you only have 2,3,4 keyfile, the order is not a very relvant security, as you would only need 2 try, 6 try and 24 try to bruteforce it by trying all combinaison.