"Fewer people are here" - Should this be accepted?
This is what I used.
I wrote "less people are here" and was marked wrong. Should be accepted or semantically different enough?
'Less' is used for uncountable nouns while 'fewer' is used for countable nouns. Since 'people' is a countable noun, go with 'fewer'.
Could this simply be "There are few people here" or must कम always be comparative?
"There are few people here"
Yes. In fact, I would vote for this to be the preferred translation.