Got it.
Although, if it's supposed to give a translation-like feel I assume it's not used often in daily conversations? Gives off a bit of a "pompous" feeling, no?
So basically, from what I gathered - the Chinese 所謂 was transliterated to "謂う所の" which was reworded to いわゆる with the Chinese kanji 所謂 still left intact?
So the Japanese borrowed the relative pronoun usage of "ところ" from the Chinese "所"?