Lol, I wonder which word it was. If it were part of a name, I don't see how that would be a big deal, considering Japanese names in general (how half the time the spelling is odd). If it were a normal word, that'd be pretty funny.
No, they were ordinary words like this: 怪我, 完遂, 焦眉, 順風満帆, 措置, 思惑, 低迷, 破綻, 頻繁, 踏襲, 前場, 未曾有, 有無, 詳細 Can you read them? I can read most of them correctly, but not every word.
Recent children names are completely insane. Parents assign arbitrary pronunciation to any sequence of Kanji characters. It will be nightmare if you are a teacher and need to remember the names of all the children in your class.
One time my friend went to this one website that he likes to go to that's in Chinese and wanted to see how many character meanings I understood just by knowing Kanji. I got a few meanings correct and others had different meanings in Chinese; it's also interesting to see characters that have similar readings.
I can guess some of the meanings of this kind of Chinese poem.
I've seen Mireru plenty before, and maybe it wouldn't be wrong to simply consider it slang?
Strictly speaking, it is grammatically incorrect. But I guess it will eventually become a part of the language.
The difficult thing about old Japanese is the lack of definitions in Japanese->English dictionaries.
I don't know if there is a dictionary for archaic Japanese <-> English. This is online archaic Japanese dictionary
, but of course you need to know modern Japanese first.
(By the way, that site has good dictionaries of English<->Japanese, Chinese<->Japanese, Korean<->Japanese, and even sign language <-> Japanese!)