Is my interpretation correct?

That sentence is ungrammatical and its meaning is unclear.

Thank you very much.

I wonder whether it was meant to say this:

The joys of childhood should be such as children extract themselves.

Let me try with this example.

The things she let me know were such as I considered important.

1. "things" is ommited after "such."
2. "as" in this case is a relative pronoun, as in the following: Choose such friends as will benefit you in the long run.

Is my interpretation correct?

teacherJapan1. "things" is omitted after "such."

You may think of it that way.

teacherJapan2. "as" in this case is a relative pronoun,

No. 'Such' is the pronomial.

teacherJapanChoose such friends as will benefit you in the long run.

There is no pronomial there. 'As' is a conjuncti

teacherJapan2. "as" in this case is a relative pronoun, as in the following: Choose such friends as will benefit you in the long run.

Personally I think this is a reasonable interpretation. I find it hard to see how "as" can be a conjunction here. On the other hand, opinions may vary.

Mister Micawber10.with the result or purpose: He said it in a voice so loud as to make everyone stare.

Well, at least one dictionary agrees with me... Or I think I should I say that I agree with one dictionary.

Mister MicawberWell, at least one dictionary agrees with me... Or I think I should I say that I agree with one dictionary.

I would say that the use of "as" in the original sentence is more like sense 3, pronoun, at http://www.merriam-webster.com/dictionary/as :

GPYOn the other hand, opinions may vary.

Indeed.

Thank you very much for your answers:-)
It's always wonderful to expose myself to differing opinions to clear my head:-)