That is correct. WM defaults to 2625m, and Unreal defaults to 100 in the Z scale, when it should be 512.6953125 using the default WM value. Since you changed yours to 2500, your Z Scale should be 488.28125.
Honestly, I don’t know how that number (0.1953125) was reached or why people think it’s THE number to use. I’ve always found that it makes my landscapes WAYYY over stretched, vertically. If it looks right to you in Unreal, then I say use it. Personally, I’ve found 100,100,125 to be close to perfect for matching World Machine’s height on a 2625m world.