I got the same results. But, what do you exactly mean when you say Microsoft Update don't recognize it, does it offer to you 3.5 SP1 langpack for downloading?
No! It offers me to download 3.0 SP2 Language Pack.
3.5, 2.0, 1.1 are all OK.
I've just noticed, that MU site offers it again with "original" 3.0 SP2 Language Pack installed. [link]
So i think it's a Microsoft Update bug. (it wouldn't be the first time)
You might build a workaround for this.
BTW i don't understand why the "original" Langpack 3-times bigger (as installed) than the script made one.