yeah you're probably gonna have to escalate, rank-and-file coinbase CS reps only really have the ability to help with things like ERC-20 tokens sent to wrong ERC-20 wallet addresses, not so much access to the custodial wallets (for obvious reasons)

the reason they're not understanding is because they more often get the "i sent bitcoin to the eth wallet lol can u help" question and their preprogrammed answer is better equipped to address that question, which is not the same as your question