No it’s 15 ports max per controller not in total So yep you can totally bring back those 2 maps and yes that’s spot on, the physical port is what you list it as regardless or if it’s usb 3 or 2.
Please do try using SSDT Plug and SBRG, the way your know if it’s working or not is look at your power saving options before and after and with the SSDTs enabled you should have the options for power nap and wake up after power failure.
SSDT SBRG contains EC and other fixes so you wouldn’t need SSDT EC usbx if SBRG is working for you. In that case you would use SSDT USBX instead. (Pinch it from my EFI).
im not sure if either of those SSDTs will work correctly with you b450 but do let me know the results.
Good Luck Buddy