Daniel I understand the time zone confusion as I'm regularly having to navigate different time zones and convert meeting times. We also had this problem in the former Community.
We looked into improving the time zone feature at the get go but didn't find any existing Flarum options that would work with event setting. I'll share your feedback with Djole and we'll take another look as this is a crucial piece to the whole event experience.
I personally prefer World Time Buddy fyi.