Thank you, @ccstone!
I was actually reading that post when I saw your reply!
It's been really fun learning about this stuff. I'm still very new to all of it, but I feel like I'm picking up a bit more every time I work with these examples.
The macro you posted was super helpful—the action that I needed was the one below.
I've been using the "Trim spaces and convert to sentence case" macro that I found at this topic and modifying it as a text cleaner. I tweaked the action below to look for punctuation and add a period at the end of the text if needed. So far it's working great!
I really appreciate you taking the time to respond. I feel like my understanding of how to work with variables just leveled up!