It’s charts like this why payroll providers exist. See the relevant _Bits About Money_ post at https://www.bitsaboutmoney.com/archive/payroll-providers-pow...
Where I live (New Zealand) holiday pay got complex, and quite a few civil service payrolls got it wrong (IIRC by a few different providors). It tooke years for anyone to notice, and has taken years, and billions, to put right.
Keep it simple. Please
I joke, but a little serious when I say asking bureauracies to get details correct, quickly and consistently might be too much, let alone with software that could threaten jobs and meetings. Canada had a payroll implementation failure in government that received international attention: https://en.wikipedia.org/wiki/Phoenix_pay_system
Having implemented more than I've wanted to - too many are still anchored in the past on a mainframe, abstracted away with a web and/or mobile app.
Still worse, many payroll providers, particularly one of the very largest in Canada, actually still processes payroll according to a "model" that's manually run. It's an excel model, run manually by people. You deal with people directly. Do anything off a beaten path? Guess which model to win.