Which datepicker library does Chronoforms 8 use and how is it possible to change the week start day to monday?

Question

I have a Joomla website that uses Chronoforms 8 and I want to change the starting day of the week from sunday to monday, ie. the locale to fi. There is no documentation on Chronoforms' website on this issue and this specific version. The datepicker seems to be initialized in the file administrator/components/com_chronoforms8/assets/nui.min.js. I found a possible candidate for a javascript framework called "Nui": https://github.com/netherjs/nui However I am no way confident that this really is the framework Chronoforms 8 uses. The documentation of the mentioned framework has nothing about a datepicker. None of the arguments given to the constructor in nui.min.js hint anything about the ability to set a locale or otherwise tweak the starting date. So if there is any knowledge out here about the precise framework used, so that I could learn from it's documentation, I would highly appreciate it. Answers on how to actually change the starting day are also appreciated. "It can't be done" is also an acceptable answer. In that case a suggestion on how to replace the datepicker with another one would be the absolute ninja move.