The game is more translatable than you may think, the solution is already in the game.
TL;DR, instead of translating linguically tricky puzzles into other many languages, we translate those puzzles into Erajan, expand the Erajan vocabulary list, translate that vocabulary list into other languages, and add an in-game permanent upgrade/item that allows for the translating of Erajan easily in-game.
The biggest flaw with this game is its complete and total lack of translations, and the supposedly impossible task of translating it. Tonda Ros, the creator of the game, has stated "There are certainly no concrete plans [for localization] because it is largely considered near impossible."
Nothing against Ros, he did doesn't want to get burned out and he shouldn't stress himself over making sure a translation has the exactly correct implications of every word of every puzzle. I just want to argue that it isn't near impossible, and is instead plenty possible. While many of the puzzles rely on English word games, many can either stay English or have ways to be translated (even if they are less than elegant).
As for all that needs to be translated, our main concern is the puzzles. As an example, the many painting puzzles that involve two paintings of objects with names one letter off from eachother. In translating the game, you would have to change all of these paintings to different paintings, and also come up with a translation that is exactly 44 letters long for the main painting puzzle. How do we manage this?
We actually have a convenient tool here for in-lore language translations: Erajan! Instead of painstakingly finding a unique translation for every language that fits in perfectly, we can find an Erajan translation, and then add an Erajan to Native Language dictionary in-game. It isn't completed either, with a total of... 46 known vocabulary words/affixes... blue prince is so damn good... anyways, while we may lose some beauty, we have the ability to add words that don't exist to fit a given puzzle.
So, for our picture puzzle, the output is "If we count small gates eight dates crack eight safes", we have two known words. Gate is Yait, and Small is Ma. Under proper Erajan compounding, adding a specifying suffix of Je, meaning Outer, we would get Mayaitje. This is two letters shorter than SmallGates. To solve this, as well as reduce difficulty in reading, we can add a space before and after Mayaitje, creating the ten character " mayaitje ". While some languages don't have spaces, the idea of the space is pretty easy to pick up on. The space-containing can simply be blank, with the in-lore explanation being that the paintings were ordered on short notice and couldn't be completed.
"Eight," like all numbers, don't exist in Erajan, but could be added. There are many directions an Erajan number system could go in, would be cool if it integrated the math system in since it has a mirroring operation. For now, let's say "Forsi". "Date" doesn't exist, but could be Daulor for Date (literally Day Letter). "Crack eight safes" could be Forsipuzelcol (eight safes unlock, puzel being safe, col being unlock).
So far, we have "mayaitje forsidaulor forsipuzelcol", meaning "small outside gate, eight dates, eight safes unlock", 34 letters so far. An extra 9 letter word can be added that means "including", which for the sake of brevity let's just say Including in Erajan is Including, we get "including mayaitje forsidaulor forsipuzelcol".
Now, if you are like me, reading Erajan is very difficult for you, and translating each affix into english and stringing it together is a headache. Worry not, for you can now unlock the Mavolterajalormora, literally the small electric eraja word world, which is a pocket translator! Simply type an Erajan word in, and get its meaning in your native tongue!
For example, if you type in Hew, the dictionary tells you House, the definition of House, and the word is added to your dictionary. This also adds the word to a word bank folder on the device, which tracks all of the words/affixes you have added.
Another example, if you add Forsipuzelcol, you unlock three words: Forsi, Puzel, and Loc/Col. First the game shows you an interpretation of the original word (unlock eight safes), the literal meaning (eight safe unlock), and the definition of each of those words. You could (maybe) even put in entire phrases and get a complete translation out of it.
So, the puzzle of translating the game's puzzles into several languages has been reduced to translating the game's puzzles into Erajan. An update would have to add the trusty Mavolterajalormora, perhaps as a reward for solving a puzzle, and I think it would have to be a permanent inventory item. Another thing that would need to be added is probably a basic ABCs book that shows the ABCs in order, useful for some puzzles.
Also of note, this isn't all puzzles. For example, all of the parlor brainteasers can be translated mostly directly to other languages, or be remade with a given language in mind. I worry for some grand puzzles with several moving parts, such as stuff relating to A New Clue, but I'm sure there is a way. Possible until proven impossible.
Are there any puzzles that you think are truly impossible to translate?