Gmail Auto Reply to Forwarded Email Possible?

So I’m trying to set up a very specific thing: I have a gmail account and a cloudflare domain.

I need to have five different email addresses at this domain. Let’s say 1 - 5 (at) far, this forwarding has been working fine.But what I need is, through gmail, to have a filter, where if the To field equals a specific address, reply with a certain template.

For some reason, when I set this up, Gmail auto replies to <long_string><from_sender>, as opposed to the correct from sender.

I understand this has to do with Cloudflare changing the sender in the envelope, but I feel like there must be a way to set this up correctly.

Has anyone done this before and can provide any pointers?
Thank you!

I haven’t tested, however I believe this could be done via Email Routing and Workers to get auto reply.

Edit custom address so the action is Send to a Worker.
Then in the Worker, you’d specify to which address you forward the email (your Gmail) and also add optional field for example.
Then the field is visible on your Gmail.
Using Gmail, you create auto-reply to field.
Otherwise, you could create an auto-reply action with Worker itself.

Thank you for the suggestion! I tried using email workers, but couldn’t get any of the email auto reply or sending (based on the docs) to work. I tried both with the web editor, and using wrangler to edit the project locally and deploy it.