For windows with test signing on it seems you may be able to replace the tables with your own generated ones similar to the OP's original attempt, but without the need to use grub. I have no idea the utility of this, considering it requires test signing and compared to the grub approach, but maybe it will come in handy to somebody someday.

> To do this, rename the AML binary to acpitabl.dat and move it to %windir%\system32. At boot time, Windows replaces tables present in the ACPI firmware with those in acpitabl.dat. [0]

[0] https://docs.microsoft.com/en-us/windows-hardware/drivers/br...