I am still not able to get the required information.
I am summarising my requirement here:
1. An external user drops a file into a team folder that is shared to him externally.
2. I get the event and got the namespaceId of the folder from the event. I can confirm that this is a team folder using the 2/sharing/share_folder. Now we know that team folders have same path for all users in the team, so how can I find that path (respective to the enterprise root) of the namespaceId.,