Open the Holidays Tab, and press the Export icon in the toolbar at the bottom of the screen:
You will be prompted to choose to which Calendar to export the holidays of the next 12 months ahead. You can pick any Calendar defined in your iOS system.
NB: All the events within one year from now, will be transferred — and only these ones.
If, in the Settings screen, you had activated the option to show your user-defined anniversaries in the Festivals list, they will be transferred too.
You may repeat later the Export operation as often as needed over time, if you wish to transfer more upcoming events. The program does not create duplicates in your calendar, so you don’t need to bother about overlapping.