So I made a file History/AssetsSaxo.csv with the following:
Name,Price,Spread,RollLong,RollShort,PIP,PIPCost,MarginCost,Market,Multiplier,Commission,Symbol
EUR/USD,1.14174,0.00015,-0.0977,-0.1095,0.0001,0.1,-1,0,1000,0,EURUSD

With the symbol EURUSD, I also tried EURUSD.FX and "EURUSD"

However, this feels like shooting in the dark. I'm also unsure if the file gets read at all? The plugin is called Saxo, but in the UI it is called Saxo V2. On Saxo's website, there is nothing like V2. Just their Open API.
Attached a screenshot from the Saxo Open API documentation.


Output is still
Z2.94: X PH H4 B0 V1 SF0.0 - EUR/USD history unavailable!