I hear what you're saying about the account showing up as an option in the expenses tab on a bill and will share that feedback with the product development team.

I want to make sure I'm following what you're trying to do. Since you're not using items, are you recording your sales in another way and then trying to have the COGS account affected by using the expenses portion of a bill? If not, can you please give me more details about why you're trying to record a COGS account in an expense? Knowing that may help me find a solution for your question.