A steeper curve would require more processing power than is currently available in the input channel (the filter is essentially applied multiple times), so I’m afraid this is highly unlikely.
Avantis and dLive have larger FPGA’s with more processing per channel (and more channels), so they can include both HPF and LPF as part of their input channel processing, though note that the LPF has a fixed slope, and the PEQ block (which is the same in all XCVI cores) also has fixed slopes.
Sorry!
Keith.