Thanks for this observation !
In our case there is a small manual process (after purchase), where we assign the service to the customer, so at that moment we use the "convert" option in WP-Client. I've been testing this way of doing it and it works OK, for now..... :-)
The only downturn, which i have asked wp client support about is that WP Client is using the "First Name" field as the company name, and this isn't good, I need it to use the woocommerce "Company Field". This value is important as you can't change once it's assigned in wp client....