Are you having trouble adding or selecting your location when your device isn't in English? I'm really sorry about that - this is a known issue that I'm trying to fix and update as soon as possible.
In the mean time, here are two things you can try:
For example, if you search for "Berlin" and the following two locations come up:
Berlin, Germany
Berlin, Deutschland
Select the English version (for example "Berlin, Germany").
a. Go to Settings -> General -> International -> Language and then select "English"
b. Your phone will take a few minutes to switch over to English.
c. Once that's done, go back to Climate Clock and then type the your location name in English.
d. Your location should appear and you should be able to add it.
e. Once it's added, go back to Settings and set your language back to your original language.
Sorry for the trouble! Again I hope to fix this as soon as possible and thanks for your patience!
And if you still have trouble, please email me and I'll try to help as soon as I can.