Translation guide
A phrase used to indicate that you are using an expression that is not literally true or exact, but gives a general idea. In Japanese, there are several ways to express this depending on formality and nuance.
To signal that what you are saying is not meant literally, but is a way of describing something.
He is, so to speak, the face of this company.
That is, so to speak, a dream-like story.
Literally 'if you try saying it', used similarly to 'so to speak' or 'in a manner of speaking'. Slightly more conversational than いわば.
He is, so to speak, a modern-day samurai.
Often translated as 'so-called', but can overlap with 'so to speak' when referring to something commonly known by a certain name. Note: it directly modifies a noun.
いわゆる is used before a noun and often implies 'what is generally called'. It is not a standalone phrase like 'so to speak'.
He is a so-called genius.
A more formal or literary version of 言ってみれば. Used in writing or formal speech.
The plan is, so to speak, a castle built on sand.
To soften a statement or indicate that it is only partially true.
いわば is an adverb that can be inserted into a sentence to mean 'so to speak'. いわゆる is a pre-noun adjectival that means 'so-called' and must be followed by a noun. Do not use いわゆる as a standalone phrase.
He is, so to speak, a walking dictionary.
He is a so-called walking dictionary.
In casual conversation, you can also use っていうか (tte iu ka) to rephrase or soften a statement, similar to 'I mean' or 'like'. However, it is very informal and not a direct equivalent of 'so to speak'.
So to speak, it might have been fate.