Euro on a account in France what they obviously don't have. And they have a Thai Bank account already so they can use this for the non-O in France already, only need to make sure that there is the money embassy wants. Or they can transfer 800.000 baht to this account and apply for a non-O 1 year visa if this is avaible in france
when it expires it expires , then you have to make new visa in the embassy. When you leave Thailand on any extension in your passport without a reentry permit then it's automatic cancelled.
Why someone should have a problem when he leaves the country and still have a ED visa. Thausends of school kids with ED visa leaving in holidays Thailand and never have a problem. My son did this may be 20 times in 8 years. There is no law that people have to cancel an extension.
Get a written confirmation from the airline that the flights are cancelled, german embassy is closed now, but may be open until you need it, they could give you a confirmation too. And go to the immigration asap to find out how they react.