I was working out the K4 keys for the Aristocrats and Patristocrats in the MA 2019 Cryptogram and wrote a K4 worksheet program to save myself some effort. You can drag the alphabet columns around to arrange them in a likely order. You can enter suspected key words and put them into the key alphabets to see if the corresponding substitutions look like they contain the other key.
A link to this program is:
Any bug fixes or suggestions for improvement are welcome.