'Ospiti a casa' just means 'guests at home'. The point, according to me, should be to always try and translate as literally as possible, so that the sentence makes sense in both languages and the lessons Duolingo wants to teach are learned. Since there is no need to translate 'house guests' here, which by the way is transforming two nouns in Italian to one in English, you can just go with what the Italian actually says.
One possible reason "houseguest" would not be correct in this instance is because that would leave of the location of the guests. The sentence is constructed in such a way that there is both an object (the guests) and a location (at home).
Additionally, I don't think "ospiti in casa" can translate into "guests of house", (ie, houseguests). To use that construction, it would need to be "ospiti DI casa", which I'm not even sure is a proper term in Italian.
Finally, "in casa" is one of those unusual constructions like "in bagno" or "in doccia", where there is a "missing" article that is implied. "In bagno" means "in THE bathroom" and "in casa" in this construction means "in the house" or "at home".
Again, maybe it is a regional or "Americanized" thing, but "Guests in my house" or "Visitors at my house" or may variations thereof are commonly referred to as "House guests". I often have wine nights at my home, and many times have told my wife "We are getting some house guests tomorrow".. It would mean we are having people come over to the house for an event or dinner or whatever.
That is certainly possible. And one of the accepted translations of opsite is actually "houseguests". But my point is not whether or not the noun can mean "guests" or "houseguests". Rather, I wanted to address to some of the earlier questions about the phrase "ospite in casa". If you combine these words into "guests" or "houseguests" you are leaving out the portion of the sentence that indicates the location of the guests. So while Duolingo would perhaps accept "I often have houseguests at home" (but I'm not brave enough to try it...anyone given this a shot and it been rejected?), the portion of the sentence "at home" can't be combined with "ospite" to create the noun "houseguests". :-) Someone had earlier asked if "companion of my room" meaning "roommate" was an equal comparison to this example. My point is that it is not: In that case the construction "of the room" as opposed to just "at home" is what made "roommate" the correct selection. To construct the phrasal noun "houseguest" using the same idea would need to be "opsite della casa" (Guests of the house, where the normal construction "of the" to indicate the type of a noun is used. (Guests of the house, as opposed to just guests). :-)
I simply translated it into "I often have guests at home (a casa)" without wondering about the implications others have noted previously. But I live in Canada and to me the phrase is quite inclusive. To us, anyway, guests can mean anything from paying customers to friends for coffee. I simply assumed the same could be understood from the Italian. I do want to say however, that DL is quite inconsistent in its expectations of literal or idiomatic translation. I've noteced that quite often.
Forgot about this question until I got it wrong again for putting "House guests" during strengthening. The previous question takes "Companion of my room" into "Roommate", another takes "Companion at work" into "Co-worker", so taking this to "House guests" seems right. Again, it may be a regional thing, but that is what they are called where I grew up.
There is the difference between *a casa" and "in casa" in Italian, the one meaning 'at home (proper)', the other phrase "in casa" trying to refer to a locality that continues belng 'my home', but is lacking the property of being the guests' home; could the phrase "at my home" or "in my house" be a solution, to serve as cognates for the Italian "in casa"?
Native English speaker here. We have the word 'houseguests' which would almost always be used rather than saying 'guests at home.' Houseguests refers to people staying more than one day and I'm not sure what this Italian sentence actually means by 'ospiti' --- a dinner guest, etc. or a houseguest?