You should be able to change "Other OS" to "Windows 8/10" or something to that effect without issue. You can also enable Secure Boot as well without issue (been there done that).
That said, I find it odd that System Information is contradicting the BIOS, as System Information gets this info from the BIOS. Perhaps just changing the OS from other to Windows 8/10 may solve? Let us know.
Many thanks for your reply Andrew and sincere apologies for the delay in responding.. the only options I have are Other OS or Windows UEFI Mode so I may try changing to Windows UEFI Mode in the hope that improves the boot time; a little reticent to do so in case it causes problems however...
Not sure I can help any further as I don't know your BIOS and would need to rely on you for the info there. What I posted was based on my Intel based Gigabyte board.
That said, I will you should be in UEFI mode as that's what Windows 11 uses. Outside of that I can't help and especially since you're already hesitant to do mess about the BIOS. Perhaps a call to Asus may ease your fears?
One thing I would add is to make sure backup before doing anything in case something goes wrong should you attempt to delve further.