same config for uefi and legacy

[NiKiZe]

What you are talking about here is the iPXE script (config is what is done at compiletime)

Yes use the same script, you can write it to be compatible for both legacy and uefi.
Actually in your case with the example so far

kernel wimboot
initrd BCD

would work just fine.
but for example, use the concept from below:

initrd -n BCD http://x.x.x.x/Boot/bcd BCD
initrd -n boot.sdi http://x.x.x.x/Boot/boot.sdi boot.sdi
initrd -n boot.wim http://x.x.x.x/sources/win10.wim boot.wim

the best example here is the last line, the filename on the server is win10.wim
the -n boot.wim is what gives the name for EFI
and the last boot.wim is what is used in legacy.

This is just part of an example for how to boot from http,
If you have a working setup, just add the filename after -n and at the end and you should be fine.
Also note that if it already has the correct name on the server, you don't have to specify it double.