Everything's going to be fine! In fact, this faux pas of mine has actually turned out to be a blessing in disguise.
Before adding something to neutralize the vinegar, I decided to check first to see if the plants preferred acid or alkaline soil. It's a good thing I did because they have quite different preferences. The waffle plant likes a neutral pH and the bromeliad likes it acidic. When I checked the pH, both plants were in fairly alkaline soil.
Having already rinsed the leaves thoroughly, I drained any excess water from the container and then added an ounce of white vinegar to a cup of water and watered the waffle plant with that; it likes it wet, anyway. The bromeliad doesn't want to just be neutralized, but acidified, so I used a bit more vinegar and tried not to get it too wet because it doesn't like that much.
Given all this, it looks like my accidental spraying with vinegar did not and will not do any real harm. Now that I know what pH they prefer (and why didn't I check that before?!), I'll keep an eye on it.
Thanks again to everyone who responded! And if you accidentally do what I did this morning, now you know how to fix it.