This is how I got it to work as intended: 
1. Install Fastscripts
2. Set up an Applescript, which looks like this: 


    >         on run
    >     	-- Copy the currently selected text to the clipboard
    >     	tell application "System Events"
    >     		keystroke "c" using {command down}
    >     		delay 0.5 -- Wait for the data to be available
    >     	end tell
    >     	
    >     	-- Get the selected text from the clipboard
    >     	set selectedText to (the clipboard as text)
    >     	
    >     	-- Call the Python script and pass the selected text
    >     	set translatedText to do shell script "echo " & quoted form of   > selectedText & " |
    > /Library/Frameworks/Python.framework/Versions/3.11/bin/python3
    > /PATH/TO/MY/SCRIPT/DK_openAi.py"
    >     	
    >     	-- Put the translated text back into the clipboard
    >     	set the clipboard to translatedText
    >     	
    >     	-- Paste the translated text
    >     	tell application "System Events"
    >     		keystroke "v" using {command down}
    >     	end tell
    >     end run


- REPLACE THE PATH TO THE PYTHON ("/Library/Frameworks/Python.framework/Versions/3.11/bin/python3") WITH YOUR PATH
- REPLACE THE PATH ("/PATH/TO/MY/SCRIPT/DK_openAi.py")TO WHERE YOU STORE THE PYTHON SCRIPT

3.Set up a python script that looks like this: 

        import openai
    import sys
    
    # Read the API key
    openai.api_key = 'YOUR-API-KEY'
    
    # Get the selected text
    selected_text = sys.stdin.read().strip()
    
    # Call the OpenAI API to translate the text
    model = "gpt-3.5-turbo"
    language = "Danish"
    response = openai.ChatCompletion.create(
        model=model,
        messages=[
            {
                "role": "user",
                "content": f"Translate the following text to {language} without changing the formatting: {selected_text}",
            }
        ]
    )
    
    # Grabs the response from the API and strips it of leading/trailing newlines
    translated_text = response["choices"][0]["message"]["content"].strip()
    
    # Replace the selected text with the translated text
    print(translated_text, end="")

- Replace "YOUR-API_KEY" with your API key and save according to the path defined

4.Set-up shortcuts to run the apple scripts via Fastscripts