My professor advised me to mention it, but not to dwell heavily upon it. I highlighted with an anecdote in the first paragraph my naivete about language learning, then said: "I wanted to learn German as quickly as possible. I thought study abroad would be an instant fix. I didn't succeed and realized I needed to get back on track. I took a two-year hiatus, focusing on writing, language learning, etc. [then came back, succeeded, etc.]"
One of my letter writers is the German professor. I haven't seen the letter, but I'm hoping she can vouch for my German abilities.
I'm hoping that puts a positive spin on it, but it's rather nerve racking.
I'm sure that many have experienced the Siren call of Europe before, too.