Please let me know if you can think of additional features to be added to this tool that would make it useful for you.

If you are interested to play with the source code itself you can find that here.
https://www.astranos.org/MiyamotoMusashi/BattleGround.php?course=9

If you don't want to code but still contribute, you could help to translate it as well.
Simply click on the Japanese character to open the translation dialog.
You can sign up on https://www.AstraNOS.org for free.