I hope you're well. I will try to share my experiences trading XDEV in the coming weeks. In the interim, did you arrive at 8 days look back period for the Williams %R for a reason?
Additionally, I noticed, when calculating Williams %, you are using the 8 day SMA of the HIGH and LOW and not the MAX and MIN of the HIGH the LOW.
You use AVERAGE(BD2:BD9)
Others use MAX(BD2:BD9) and MIN(BE2:BE9)
Did you find using the 8 day SMA rather than the MAX or MIN better? Did you choose to use the 8 SMA of the HIGH and the LOW instead of the MAX and MIN for a reason?
I think your way of calculating Williams %R contains more information by distinguishing between overbought and oversold and REALLY overbought and oversold periods.