I am positive. Every time you think it is working, it is actually just Eos auto-casting. The issue is not that Eos does follow <f> macros. The issue is the <t> line will execute a self-heal so it will not have a chance to execute the <f>. I have not tested to see if <f> will trigger a self heal with no focus target, so I am not sure whether it will work the other way. It is easy enough for you to test. Just make a macro with /pac Embrace <f> as the only line and see if it makes Eos heal herself or if nothing happens. If I had to guess, I think it would probably self-heal.
The other issue with having the tank as your focus target is that you can't focus target to watch the boss's cast bar. Doing easy content or trash, you could spend most of your time DPSing, but in a tough fight, your main target will fluctuate as you heal people so you won't be able to consistently keep tabs on the boss without focus target. Most of the time it doesn't matter, but in some fights (like T5+6), it is necessary to see what the boss is casting.