When you want to use the API Version 3.1 (actually in preview, https://docs.microsoft.com/en-us/azure/cognitive-services/text-analytics/whats-new) with Power BI and you used before the Version 2, you must do some changes. The first change is, that you must use another URL with the region inside, e.g.: https://northeurope.api.cognitive.microsoft.com/text/analytics/v3.1-preview.1/
The next change to identify the language is very easy, because the returned JSON field names not detectedLanguages in this version, the name is only detectedLanguage without an “s”. Okay, easy, right? To detect the Key Phrases there are no changes. But to detect the sentiment there are more changes to do. You see the M code below, the JSON gives us now the confidence score and it delivers three columns for positive, neutral, and negative. Before you get only one column. Mostly it is enough to analyze only the positive column, because when it contains a small number, it is more negative, when it contains 0.5, it is neutral. So, you can expand the columns with M and use only the positive column and start to analyze the data.

Attached you will find an example Power BI Report