One topic challenge for the smart guy in stories is that the party finds some texts in an ancient or otherwise rare language and need a translation. Now, you could just have them roll and give them the translation on a hit. If you want to make it a bit more complex, these are some ideas.

One word per success

This requires that you actually have a translated text in another language and show it to the players. They can try to figure it out by themselves. On a successful roll, they may ask for one word, per degree of success. If you use this method, you should have some idea what languages your group speaks. I once sat in a Cthulhu oneshot with a friend and the GM produced some Latin text. Little did he know, that we both studied Classics so could just read it. (Also if you need anything translated into Latin, just ask. By now, I’ve taught at university level for several years.)

If you want to pretty sure your players have no capabilities with the language you can grab some constructed language or do some conlanging on your own. If you want some intro, I recommend David Peterson’s youtube. He’s the guy who worked on Game of Throne and Defiance TV series.

Making translation real-ish

If you do not want to fiddle with a foreign language (or ask someone to it for you), you can exploit the truism that tranlation is hell. Something that works of fiction get wrong on in most cases. Even ad hoc translations are usually depicted as perfect in the target language, and often include knowledge someone just reading the text just cannot have.

Anyway, one constant pain is dates and measurements. They still are nowadays because some refuse to use the metric system, which kills mars probes, but that problem is much worse with olden texts. So on a hit, you could give them the translation, on a good hit, the conversions.

Similar problems occur with plants and small animals. We know that some “Blue-Fish” was pretty tasty in one Italian town, but we have know idea what species of fish they are talking about. In some cases those species might also have gone extinct, which could be a further problem for magic ingredients in RPGs.

There might also be technicalities that were clear to informed people the time, so no one spelled it out, for example rituals performed in a Greek manner. I guess some specialists may have gathered clues what that means, but I haven’t looked it up, so would probably fail that roll as an RPG character. Of course such things might be good opportunities to fail forward. If the magic circle is to be drawn in “the manner of the Lizardfolk”, you can ask a Lizardfolk mage, find some other expert or try to wing it.