I'm curious - Where in the phone does the location go wrong when the display language is changed?
With an active SIM card inserted the phone and the Android OS knows approximately where it is located.
When location services are enabled apps can access the location of the phone.
I have added UK English as a secondary language on my Nokia 6 in Denmark (Android don't speak Danish yet). After installing the required files for keyboard and speech, I can change the display language on the phone to UK English without any side-effects, or at least nothing I'm aware of?
Android doesn't support Danish?! I thought it was a modern OS...
One of the most annoying things I found with my Lumia was that it couldn't cope when I wanted to use English voice recognition but I'd bought the phone in France - what?! When the mainboard was replaced under warranty and came back with a global product code I could use whatever language location combination i wanted.
So, I hope I never see this stupid restriction on HMD phones.
Google Assistant and its voice commands does not support Danish (yet) and the preferences for it are greyed out when the display language is set to Danish. - Not being able to adjust the preferences is a bug since the phone listen and responds to 'OK Google' on any screen.
(I disallowed access to the microphone for the Google app as a workaround).
I have no issues adding other display languages, keyboards and speech, and can toggle between those installed when needed.
There will be issues regarding local news, and maybe some bugs lurking regarding calendar preferences etc. but that's another story.
Similar to Microsoft, Google only want feedback and bug reports via the feedback options in their apps and in Android.
There is sadly no point discussing Android and Google app issues here or in Google's own forums, except as pastime on a rainy day ...