Translation:No one knows where the party will be located.
The two words can be used almost interchangeably. Located simply refers to where something is. Situated is a bit more specific and most often refers to an environment rather than just to an address.
eg. Located at 101 Glory Street
& Situated on a tree-lined boulevard in a tony office park
Situated would sound a bit stilted here. But, if that's how you would like to say it, please report it via the flag button.
This sentence is very good in both languages. Personally, I would worry more about the crucial aspects of the French language being taught here:
- Negation word (personne) used as a pronoun.
- Sait vs connait
- The sentence construction with où clause
- Reflexive verb (se situera) used to form passive voice -- especially difficult and important.