Hi Koen,
I believe the display of a localized date-time attribute is controlled by the Browser -- since your browser is listed in GMT+1:00, it will always display the localized attributes in that manner. If you change your OS time zone then you should see the date-times that you're looking for.
Setting the timezone for an account, I believe, affects how the data is interpreted on the server. When you run a microflow and it references the localized datetimes you're referring to, you should see the "Session time:" portion equivalent to the time zone that you set for the account. The "Export to Excel" functionality is completed by the Mendix Business Server, I'm guessing, and that is why you see the "properly" formatted date-times in the excel sheet.
When working with different timezones this part of the documentation is a must read: https://docs.mendix.com/refguide/datetime-handling-faq
But as stated it is the browser that influences the way how the date / time is shown. In the database everything is in UTC.
Regards,
Ronald