I did some quick and dirty formulas for the Mastery breakpoints (assuming the breakpoint is at each 1% or 89.64 rating)
I am not sure if you need to, but I put these on the Main Worksheet, I'm not sure if the variables will hop sheets
This will return the percentage of your current eclipse proc:
=Round(Mastery/89.64) + 41
and this will return how much mastery you would need to get to the next soft cap:
=89.64 - Mod(Mastery/89.64)
This works for my current gear setup because I don't have any mastery procs, but since the spreadsheet handles them as an average vs. uptime I know that would break the above formulas, I just don't know how to handle that.