Help required understanding this line from Haruhi Suzumiya novel

[lajdg]

This is one of those sentences where in theory I understand all the grammar and the words, but im having trouble working out exactly what it means:

サンタクロースを いつまで信じていたか なんてことは
たわいもない世間話にもならないくらいのどうでもいいような話だ

I’ve highlighted the particles here, as it’s a long sentence and it makes it easier to see

My understanding so far as as follows:
As for such a thing “Until when did you believe in santa clause?” (サンタクロースを いつまで信じていたか なんてことは)
as much as it does not become childish gossip at least (たわいもない世間話にもならないくらい)

now this is the part that i’m really struggling with
のどうでもいいような話だ

の - is nominalising the clause before it “the ‘not turning into childish gossip’” and using it to modify whatever comes after it

どうでもいい - means “What ever way is good” or simply ‘it doesn’t matter how’

ような話 - is saying that the it’s a "X form "-topic, X being the bit that comes before

so the whole sentence is saying somehow “as for the question of until when did you believe in santa clause, it’s is an XYZ topic”

Can anyone help me understand how this all fits together?

[Sylph]

We read this book a while ago in the intermediate book club, so it’s thread could be very useful to you if you plan on reading the whole thing.

Even more conveniently, someone asked about that very same sentence, and got some answers:

涼宮ハルヒの憂鬱: Week 1 Discussion

So, サンタクロースをいつまで信じていた isn pretty straightforward. Then, なんてことは = “a thing like that” たわもない is technically separate parts, but as an expression it means “petty” or “frivolous” 世間話にもならない Together with たわいもない, this is “petty stuff that couldn’t even be small talk” Because it’s Kyon, he further emphasises this, going on to say くらいのどうでもいいような話 That it’s “a nobody-cares sort of talk to the extent that it couldn’t even be petty stuff unfit for small talk” だが、”but” それでも “even so” 俺が いつまで [(サンタなど…

涼宮ハルヒの憂鬱: Week 1 Discussion

@Belthazar to the rescue! That sounds exactly like what we should be doing, indeed! For your example: The main point is, as usual, at the end: 最初から信じてなどいなかった I didn’t believe it from the beginning. Now, there are a few subordinate clauses: サンタクロースをいつまで信じていたなんてことは About the question “until when did you believe in Santa Claus?” たわもない世間話にもならないくらいのどうでもいいような話だが、-> 世間話 is small talks, タワもない話 is a story no one cares about (combine both: small talks no one cares about). にもならない doesn’t even becom…

Hopefully those can solve your doubts.

[lajdg]

Thank you so so much!!