It sounds weird because “there” refers to an area, not a thing, and one usually thinks of things being in areas and on things. It would be more natural to say either “they are over there” or “they are on that” in english. I translated it as the latter and it accepted my answer.
"They are on there" sounds so unnatural if not incorrect. On the other hand the most natural translations for me would be "They are over there" or "They are standing over there", but they are not accepted. Am I missing something?
EDIT: Please ignore this comment. "On there" seems to be a correct translation.
Just to get a picture how awkward it sounds, simply google "They are on there" (with quotes). Result number one is a Duolingo thread (fishy). Second, third and fourth results are misspellings of "They are on their way" or "They are on their phones".
Maybe "They are on that (thing)" is a better translation?
Sure refer to things where it is part of a misspelling. Or you can google for it and look for good sources and not just look for one specific sentence, e.g. (all clickable with varying contexts):
- "But the fact they have only got a third of the roundabout to remove and they can't remove it because people are on there,..." - BBC
- "Most of the songs that are on there are songs they played when they first started out,..." - BBC
- "He can bring his tax return....and just let people ask us questions about the items that are on there,...." - Time
You can start a sentence with daar... (e.g. daarop) and hier... e.g. hierop), since they clearly point out a location (emphasis). Whereas er... (e.g. erop) is more abstract and hence will not be the most important part of the sentence. (In Dutch things that are important/emphasised are generally put towards the front of the sentence).