Is it safe to use the extension?
Chrome store extension codes are reviewed manually by Google team, if an extension is danger on user privacy, or goes against the terms of use, they would take it down immediately. Yes, It is safe.
Is my personal data exposed to any third parties?
Not being sold to third parties, Not being used or transferred for purposes that are unrelated to the item's core functionality, Not being used or transferred to determine creditworthiness or for lending purposes
Are my conversations or contacts exposed to any third parties?
No, the excel sheet of numbers you upload directly reflects all the data onto the extension without saving anything. Your conversations are completely secure as per WhatsApp guidelines and as far as the data part is concerned, it is covered in the previous question
What all data do we collect?
We just need minimal data for tracking purpose to resolve bugs if any on the extension and for basic analytics. We collect your email and the events performed on the extension. All this information is not sold to any third parties