In (almost?) every edition of D&D is some version of a spell that will easily translate any non-magical writing or even speech. It's usually trivially easy for a wizard, and in some editions even for high level thieves. It's a bypass that lets those who memorized that utility spell avoid having to run back to town to consult a sage, if there even is one available.
On one hand, as a DM, it I can see why this can be annoying, especially if the spell has a long duration. On the other hand, it is a choice the player took to have their character take that spell. It's a slot that could have been a magic missile or sleep. It's a choice the DM should reward, or at least not punish the player for making it.
That's not to say that the spell is going to hand everything to the PC's on a silver platter. An important consideration for the DM to keep in mind that the spell translates the words literally, and that not all languages are constructed the same way. For anyone who's studied a language other than their native one, this probably does not come as a shock. Most people I know from the US took a romance language in school, French or Spanish mostly. Either that or German. Because English shares a lot with these languages there's a familiarity to them, and a lot of other languages follow different rules.
For example, I'm learning Mandarin. You know how in English (and the romance languages) there are different tenses? Past tense, present tense, future tense, etc... Mandarin doesn't. There's context clues, but a literal translation could potentially be any.
Also there's nothing that says that the words have to be in an order we're used to. Maybe they write like Yoda? Or the subject might not come first in the sentence.
We're going to the restaurant that's next to his school with your cousin.
Next to his school the restaurant your cousin is going with us.
To go further with the idea, what if there's no word in the language for restaurant or school?
Next to his reading place the cooking shop your cousin is going with us
That doesn't take into account proper nouns.
We're going to the restaurant that's next to Wang's school with your cousin Zhang.
Next to king's reading place the cooking shop your cousin open bow is going with the people.
Clearly that would be a little more comprehensible with some punctuation, but maybe the language doesn't use any?
Another trick is to have a word have more than one meaning, or to be used as a slang term.
What does it mean if the person is described as square? Bad? A herbert? A literal translation isn't going to help much there.
Do I even need to go into memes?
One last thought. Don't make it rhyme unless it's in a language the PCs speak. I always hated in movies and TV when that happens.
All of this does require some prep work from the DM, a little more than what would be required if the PCs were using a sage who was familiar with the language and help navigate it for them, but used properly, it can be a fun way to make an ancient civilization (or current but not native civilization) more flavorful.