My client has all sorts for FX rate types attached to different scenarios (Actual, Budget, AOC, LE1, LE2, LE3...). Some of these FX rate types are updated during the year.

I just go with separate FX Rate Types on the scenarios and have separate FX Rate Templates that are dynamically built with instructions. So for setting rates on a Seeded Forecast you just enter the current month and the rest populates automatically. Or for Actual CC it'll go get the current months rates from Actual and apply it to all periods in the Actual CC scenario. i'll attach some examples

these may not be exactly for your use case but the Actual CC or PY are good starting points. If you want to copy rates from one rate type to another just modify the get fx rate to take in the Source Rate Type and then in the set rate section to the right you'd specify your target Rate Type
I'd go Excel or manually adjusting if you are loading new rates. If they are the same rates being used in different scenarios, I wouldnt duplicate the rates and instead use custom translation rules.
For example, if Forecast is using the latest closed Actuals period rate... I wouldnt load that rate to another rate type attached to the Forecast scenario. I would use custom translation rules to go get the rate dynamically.