Measure that shows whether the process has been completed

jobf I believe that a situation measure like that would look similar to the following:

Situation Measure =
VAR _ProcessedArea = SUM( 'Table'[Processed Area] )
VAR _TotalArea = MAX( 'Table'[Total Area] )
VAR _Return = IF( _ProcessedArea = _TotalArea, 1, 0 )
RETURN _Return

I assume you only have Fact table instead using a star-schema here. If so please try using the measures below in your visual:

First Date =
CALCULATE (
    MIN ( 'Data'[Date] ),
    ALLEXCEPT ( 'Data', 'Data'[Plot], 'Data'[Type] )
)

Processed Area (Sum) :+=
CALCULATE (
    SUM ( 'Data'[Processed Area] ),
    ALLEXCEPT ( 'Data', 'Data'[Plot], 'Data'[Type] )
)

Total Area (Group) =
CALCULATE (
    MAX ( 'Data'[Total Area] ),
    ALLEXCEPT ( 'Data', 'Data'[Plot], 'Data'[Type] )
)

Situation =
VAR Proc = [Processed Area (Sum)]
VAR Tot  = [Total Area (Group)]
RETURN
IF (
    NOT ISBLANK ( Tot ) && Proc >= Tot, 
    "Processed",
    "Processing"
)