Translation:She downloads something from the Internet.
How do you pronounce "något"? Is it correct to pronounce it like it's written [något] or [nåt]? The same goes for "någon", is it correct to pronounce it like [någon] or [nån]? Tack.
You could pronounce it either way. It is very common to write Något as Nåt which is more colloquial. Same for Någon - Nån.
All these words mean "Någonting":
Någonting - Nånting - Något - Nåt
I used ned instead of ner and it was rejected. I thought that these words mean the same thing but that the former would be more formal than the latter...
Both "ned" and "ner" are accepted here. Are you sure you didn't have any other error in the translation? Because both work perfectly fine.
Late answer, but for anybody else wondering it's probably because of the "type what you hear" exercise bug where only the default is accepted regardless of the number of homonyms.
As far as I know, they are pretty much synonymous but in the case of ladda ner the verb is ladda ner, not ladda. It is a part of the verb and with particle/phrasal verbs, you have to use the correct particle. As far as I know, there is always only one choice.
For example, you would never say mata i or mata inne, it's always mata in.
Nor would you ever say ladda uppe - only ladda upp.
You're right about the other ones, but for ladda ner, both ladda ner and ladda ned work. It's the same for all particle verbs with ner/ned, both work. The difference between ner and ned is perceived to be only between more colloquial (ner) and more formal (ned).
But with other particles, it's true that only one version works.
Those two mean 'She has downloaded something from the internet' and 'She is downloading something from the internet', respectively. As others have mentioned, it doesn't matter whether you choose ner or ned. In compound forms though, such as nedladdning and nedladdad, only ned is used.