Is Insofar as Correct?

Use insofar to mean "as much" or "to the extent." You might, for example, say, "I will get my math homework done insofar as I can. The adverb insofar is somewhat old fashioned and uncommon these days, but it's a good way to talk about doing something to a certain degree or extent.

What does only insofar mean?

phrase. If you say that something only goes so far or can only go so far, you mean that its extent, effect, or influence is limited.

Is it in so far or insofar?

The form insofar is American English; the standard form in British and other English is 'in so far'.