Right now the default delimiter we use in the plugin and all our country package files is a comma ','.
We are changing this to a semi-colon ';' in a coming version.
The simple reason is, it offers more flexibility in CSV values.
For example, in Spain there are a few cities, which actually have a comma in the name (like "Los Saus, Camallera i LlampaiesLos").
Right now, these cities are not included in the csv file. If the separator was a semi-colon, this city name could be added.
Do I need to do something ?
Not right now. The cities which are in your database do not have any commas (unless you manually added any, which is wrong).
The city sheets you have downloaded/used in the past, can still be used. Just make sure to change the default delimiter. You can do this when importing by changing the delimiter on import, or you can set a one-time filter, which will set a default delimiter of your choice.
See this filter for more info.