Should the verb here be "tepagon" instead of "irughagon" since the recipient "īlon" is first person plural?
Yes, it can be. I'll be sure to include that as an acceptable answer. In general, though, you can use either verb with a first or second person object; you cannot use tepagon without a first or second person object.
If you know what I mean ( ͡° ͜ʖ ͡°)