Hi Finn,
Thanks so much for reaching out!
Unfortunately our CSV tool does not have that functionality available.
You can update your events manually from your Edit Events page, although if you have many events, I can understand that it may be daunting to do that.
You can also add this idea to our Feature Requests, as we tend to implement ideas based on customer feedback, so your input is greatly appreciated:
https://tribe.uservoice.com/forums/195723-feature-ideas
Let me know if you have any other questions on this topic!
Thanks,
Jaime