Hi there Damien,
Thanks for getting in touch with us!
Unfortunately it’s not possible to import recurrence patters at the time. We have an existing feature request for this functionality, but I don’t think it’s something that will be included in the near future.
For now you can import the first event of the series and the create the pattern manually once it has been imported. Or you could import all events in the series as single events.
You are welcome to upvote this feature request at The Events Calendar user voice page, where we gather feedback from our community → https://tribe.uservoice.com/forums/195723-feature-ideas/suggestions/8142342-add-a-recurring-event-option-to-csv-uploads
Please let me know if there’s anything else I can do for you,
Best,
Nico