Is that how you learned English? If so, I'm seriously impressed. Because you appear to have picked about the most difficult method of learning a language I can imagine! I seriously recommend a change of learning methods.
That said, if you're doing this just for fun, I can see how it might be a laugh. If not a confusing one.
lets tackle the first sentence.
"koro mukashi mukashi" - well, koro is like toki, meaning the time, and mukashi means "long ago", and when used twice consecutively picks up a feeling very similar to the "Once upon a time/ long long ago" of English literature.
"daremo mita koto mo kita koto mo nai" daremo means "nobody", "mita koto ga nai" means to "not have the experience of seeing something" (mita is to have seen, nai is to "not have") so, "kita koto ga nai" (kita is to have heard) means "not to have the experience of hearing something". (kita koto is to have the experience of hearing something. You can guess about mita koto, right?
)
the particles changed to "mo" to give "mita koto mo kita koto mo nai", since when you say "this and that are blue", you use "this
mo that
mo blue desu". The "mo" particle shows the two objects are strongly related.
SO, "daremo mita koto mo kita koto mo nai ....." becomes "....that was both unheard and unseen by anyone". More or less.
"fushinna jidai". Fushin probably means "suspicion" but since I dont see any kanji here, I cant be 100% sure. It might be "dullness" (a word very appropriate for me, maybe). Jidai means "age" or "era". It is usually used in the context of large periods of time, like, for instance the amount of time a person is on a throne, or even huge periods like the bronze age etc.
So, "fushinna jidai" means "age of suspicion" (I expect we're not talking about an "age of dullness" considering this is a sub we're talking about..)
Right, I'm not going to do the remaining sentences. It took long enough to do this one. I hope you can see that, with the amount of effort one has to put into each sentence, it really isn't worth it. In order to remain concise, I've more or less skimmed the grammar. To make sure it was explained in a properly understandable manner, I would usually devote an entire chapter to each grammar point, not 1 paragraph!
Furthermore, anime and dramas are littered with odd grammar, and strange phrases, since this sometimes makes for a good story, and grammar isn't at the forefront of the mind of whoever makes TV programs. So there is a good chance that by learning Japanese from either of these sources, you will end up with a very odd language skill by the end.
As such, I regard this post and the previous as prime examples of
how not to learn and
how not to teach. But, otherwise, if you're just in it for the fun, I don't want to spoil that, so long as you realise learning Japanese like this is damned difficult.