Hi, I need some clarification on how Coinbase works. If I sent bitcoins to someone with Coinbase it uses a random wallet address to send them.
More accurately, it spends outputs that were previously received at an address that is under the control of Coinbase.
Bitcoin doesn't "send from an address" no matter how many people want to believe that. Creating a transaction just spends unspent outputs. Those outputs may or may not have one or more addresses associated with them.
If the person sends bitcoins back to that random address, will I receive them in my account?
No.
If you want someone to send you bitcoins, you'll need to give them an account funding address from your account.
