Re: Insight into
That's interesting. "Insight" seems to occur in ME; I would therefore take it not as a rendering of "einsicht", but as a combination of "in" + "sight"; though perhaps "einsicht" and "insight" have a common ancestor. (The prefix "ein" can mean "one"; but in words such as "einatmen", "einbauen", "einbeschreiben", "einbringen", etc., it has the meaning "in".)
As for "insight into", even if we privately regret the apparent redundancy, there is nothing we can do about it, as that's the standard phrase (not "insight to").
Cf. "introduce X into Y", where Y = "the discussion", "the equation", etc. – no other preposition will idiomatically serve.
Best wishes,
MrP
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Not a professional ESL teacher.
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