I know just enough about acid washing to know that I'll NEVER do that again. Maddie gave you the gist, and I can't imagine how a wash alone is going to make a rough surface smoother. I've heard a weak acid solution can be used to soften a finish a little to facilitate its smoothing mechanically (grinding or sanding or polishing), but even that sounds a little iffy to me.
I would say mechanical smoothing is going to be your best bet. You'll need to drain the pool, which carries its own set of risks. I think there might be an underwater polishing solution, but it would likely be expensive.
Have you been keeping good records of your water testing and dosing? Many finishes carry a five year warranty. That would be my first stop. Contact the original installer to see if he'll stand behind his work. If he won't, or he's disappeared, it's possible the manufacturer of the finish will honor its warranty. Some of those only allow their finishes to be installed by authorized contractors, and have been known to step in on a warranty claim. But be prepared to be hit with accusations of water quality as the culprit. Which is why you may have to offer proof that you've maintained the water correctly this whole time.
That all said... Welcome to TFP! Sorry it's under these circumstances. We'll do what we can to help you. Just keep in mind, that if the first "free" solution you're offered is an acid wash, or requires draining the pool, come on back for a more thorough explanation of the possible downsides of those actions, so that you can make a more informed decision about it.
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