Experiment number one: international.com and international.com/fr
We imagined a situation where the english & international version of a website would be at the root domain let’s call it international.com since we can’t disclose the real domain name that we used for doing this experiment. Then, we created a french version at international.com/fr
We added international.com and international.com/fr to Google Search console and we discovered that the Google traffic of international.com also included the one from international.com/fr. For sure, the international.com/fr results only included results from international.com/fr
This means that in the list of queries, you would have a mix of french and english keywords as it would take into account the folder from the international version (which we pretend to be in english) and the french version under the folder /fr
Experiment number 2: international.com and fr.international.com
In this case, in google search console, we discovered that international.com only included the results for international.com and fr.international.com included the results for fr.international.com only.
Conclusion:
It is better to create a subdomain if you want to separately track two websites in different languages.