I’m not speaking for Singular, but it appears the residential voltage supplied in France is 230vac @ 50hz. This seems consistent with other European countries.
https://www.generatorsource.com/Voltages_and_Hz_by_Country.aspx
I would believe if the Maestro and Aeros were sold in the European market that the power supplies should be able to work properly when supplied with 230vac @ 50hz. A power supply that didn’t provide enough amperage may not work correctly, but the ones that are packaged with the units should be properly rated to work. Would you be able to take a photo of the printing on the adapter which shows the voltage and amperage and post it in this thread? I don’t know what the ma(milliamps) rating should be, but it should be 9vdc with a negative tip on the connector.