This is not my area of expertise, but can I ask some questions? (1) Did the Warp Engine work without the Mediator? (2) I thought the Warp Engine was a 68040 based card, so why not use the 68060 card? (3) Does it boot at all? (4) If it boots, can you "see" the PCI cards using PCIinfo command?
If it booted before the mediator, try starting with the Mediator "Bridge Board" only with no Meditor software installed; if it doesn't boot then there is a hardware conflict, perhaps with the Zorro 3 Autoconfig memory space, and if changing jumpers for the W_E MMU does not help (Mediator has a ENV: setting for the MMU), then use the CS MK3 060.