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 for 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
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 one website in the root domain and another website somewhere else in order to track Google traffic.