I love the floral blouse paired with the culottes, Jaime!
And how fun that you are going to Copenhagen. I'd say: if you love wearing your Trippen boots in those kind of temps, then why not! I bet they are very comfortable too, which is important if you will be doing lots of walking.
I would continue to check the weather forecast though. Summers in Northern Europe (including Scandinavia) have been a lot hotter the last few years.
I was in Copenhagen in July 2019, and there was a heatwave. We had 10 days of 28-32 °C and it was sweltering hot. I only wore my Birkenstock sandals:-)
It did rain one morning, so a closed-toe shoe was good to have for that.
The Uniqlo puffer is a great idea (and it doesn't take up all that much space, right).
Re: slippery. As we had so little rain, I can't really speak to that, but here in Antwerp there are now many areas with a new type of pavement that gets incredibly slippery when wet. I don't know whose brilliant idea this was, but it really is an accident waiting to happen :-(( Hopefully it's not the same in Copenhagen, but I'd take one pair of shoes with good traction, just in case...