Show the account name and line description together in the invoice
I probably misunderstand you, but isn’t that how they are already?
EDIT: sorry, I don’t know why I read journal and not invoice
Most of the users wouldn’t want to display internal information like accounting treatment on their invoices.
Your only solution would be to include the account name inside of the description field.
Make it optional for private use
The sales invoice entry form is already overly complex. What is your justification for including the posting account on a sales invoice sent to a customer?