The Location settings in Twinmotion 2023.1 can be found in Ambience > Location.
There is a known issue currently causing that problem where any media you create will show an incorrect location preventing you from adjusting the geolocation of the image. A fix is currently being tested and is expected to release in our next update. In the meantime, the workaround for this is to set the geolocation outside media mode, then to create a media, which should inherit the location.
The team is currently looking into an option that will allow you to copy and paste settings between media, which would allow you to set the same location settings for multiple media simultaneously. You can upvote this feature on our roadmap here: Copy / Paste Settings Between Images - Twinmotion Public Roadmap
Regarding the option to add a light theme, I recommend submitting this as an idea on the roadmap here so the team can look into adding this.
We can't have Paris constantly asserting itself as the centre of the universe!
While you're at it - why not place the Location dialog out of the stack of frequently changed settings? Location is something that one would only change once on a typical project and yet we have to continuously scroll through it in the Env stack while accessing common settings (Global lighting>Weather>Location>HDRI environment). It should appear at the end.
I did set the location outside media. Most often any new photo does not inherit the location. Once set, if I make changes to a few settings often TM then looses the location. This happens VERY frequently.
Additional comments on location bug - I cannot get the location to "stick" inside or outside of media. Change location, create a panorama, defaults back to Paris. Change location inside of media, Refresh the media, Quit Media Mode, defaults back to Paris. Click the supposedly Refreshed panoramic media to enter Media Mode and discover the media is defaulted back to Paris anyway. Even though location had been changed and the Media refreshed - the change did not "stick."