"Their expenses for their child are big" sounds like bad English to me. It sounds a little better with "large". I'm not saying the English sentence is wrong, but why does it sound so weird??
They are both fine, but you are correct. Big refers to the size of an object. Large refers to size or amount; hence,expenses are large.
I agree. I know an account he said expenses are 'heavy' in this context woudl be better English.
Can it be "their large expences are for their child"?
Their expenses are large for their child makes sense and is easier to interpret from the Indonesian. This should also be accepted.
I think a lot would sound better, but I've heard locals say big money.
Is it correct to say "Pangeluaran mereka untuk anak mereka besar" ?
I think your sentence is more natural, but I don't know why people don't care about the order of the words here. Maybe because the answer given by Duo lingo is fine.
Spelling mistakes are not being picked up!