I'm curious about the exact translation of the lyrics "Nevermore jamais plus/Tout est foutu". In one thread here it's translated as ".../Everything is ruined" but I think that is not very accurate.

On alizee-reflections it says ‹ Everything is messed-up ›

I love that about language... when some words don't translate exactly.....

It makes it so you have to learn "foutu" as "foutu", rather than "ruined/messed up"

I think that's sort of frustrating though..

For instance, I still have no idea what "youpidou" exactly means.

Another example is that, while I'm more fluent in English, there will be a certain term I'd like to use, but I'll only know how to express it in Korean. Now that there, is a very unusual situation for me.

Oh I know kinda what you mean! Two points here:
1. In english, we have two present tenses. I am doing/ I do. The (be) -ing ending is a more exact present tense thing, that means right that second you are. The no ending form is more a word to express that you do something in general. Like, 'I work for the department of labor'. That doesn't mean you are working right now, it means that you are employed by them, but this very second you may be sitting at your house. So in other languages that lack this -ing form or an analog to it, I feel like I'm not being exact enough. But that's just how they work. But it still feels very awkward to say a French sentence saying I am doing something without throwing in an 'etre'. As opposed to Korean, where you still use a form of 'ittda' on your sentence, but you still don't use an -ing equivalent. In French you basically say Je fais, directly 'I do.' In Korean you say 'I do am'. Though in Korean ittda is the 'do am', it mean 'to be doing', so you don't throw in another word for do or be. So while in French you still have Je t'aime 'I you love', and in English you have I love you, in Korean you have Cheoneun dangshineul saranghamnida 'I you love-am-doing'. Very formal, but yeah. And it also functions as a be as in 'I am an American' 'Cheoneun Miguk saramisseumnida' (I American person-be). In French I like their 'be' better. Because Korean's 'be' basically also means have! Haha spazz out...
2. In Korean, there's a word that means something like intense sadness. But that's not really it though, it's something like that but not exactly. I read it in a book once, but can't remember what the word was. Many Koreans I know have said there's no way to translate it. What was that word? I kind of uinderstand it too, but I just can't remember what it was. Is that one of the things you can't describe in English?

don't worry ... "youpidou" doesn't mean anything. :p
it just a childish shout of satisfaction..

Depression?

haha no not depression

You learn as we've learned our own mother tongues.... we listen to the word, how and where it was used, the tone in which it was said, the reactions people had to the word, etc.

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