Formulas in Excel do not transfer to Project. Project formulas and functions are more closely aligned with Access.

What kind of "visual alert" are you needing? When you talk about two weeks from finish - what about tasks that are less than two weeks in duration and aren't supposed to be started? Have you considered looking at Finish variance which will show the difference in the baseline finish versus planned finish?

I was able to get what I needed

TEXT 2 : [Finish]-NOW()
TEXT 1 : IIf([Text2]<=14,IIf([% Complete]<=50,"R",IIf([% Complete]>50,IIf([% Complete]<76,"Y","G"))),"NA")

and then used graphical Indicators