When I really need to get a response from a customer I will email and convo, referencing the convo in the email. I've also had customers provide me with alternate emails, phone numbers, and even requests to text! My bottom line is I will communicate with a customer in whatever way they prefer. If it is something I want to make sure is then documented within the Etsy system then I will let them know I am confirming our communication via that system and when I write the convo state as per our communication via email, text, etc
A LOT of buyers come in, buy and do not even understand they are buying from individual sellers but a large overall company.