I don't exactly get what you guys mean with the difference between "I found the empty room" and "I found the room empty". Does the first one mean "I found the room that is supposed to be empty" and the second one "I found the room which for whatever reason is empty"?
In both cases I think in Italian we would just stay "Ho trovato la stanza vuota". Help me clear this up, because I'm a bit puzzled.
Rljones "stare" used as "essere" is a regional use, mostly around Rome, it's incorrect in proper Italian. I'd also add that "trovare" in Italian is also used to express the impression something or someone gives you. If you say, for example, "Ti trovo bene" you mean "You look good/healthy to me", in your example, since there's "che" after the verb "trovare" the only possible meaning is this one -> "Ho trovato che la stanza fosse vuota / Trovo che la stanza sia vuota" = "The room looked empy to me / The room looks empty to me". For Duolingo's statement you have to drop the "che" (and the verb to be later) if you want to say "I found the empty room"
It's interesting that the English usage of "find" is very much like Italian usage of "trovare". With the sense of "discover" (scovare) we say "I found the empty room (after searching a while)." With the sense of "notice" or "judge" (giudicare) we say "I found the room (to be) empty" = "I found that the room was empty."
The similarity between the two verbs is not always easy to see. With the sense of scovare (discover), trovare is transitive; it needs a direct object. In the English sentences we are talking about, it looks as if "find" has a direct object ("room") in both forms: ""empty room" and "room empty." But only in the first case is that true; "empty" is an adjective modifying "room." In the second case, "room" is the subject of an abbreviated infinitive phrase ("the room to be empty"). In Italian, that is best rendered as a relative clause with "che fosse vuota" [or "che era vuota?], with exactly the meaning you suggest ("I saw that the room was empty" = "The room looked empty").
That second usage of "find" is easily recognizable in the expression "The judge found him guilty." Here the adjective can not be placed in front of "him" so the structure is easier to see. The meaning changes just as that of "trovare" does.
I hope this helps clarify what Maddyis7 and I were talking about. And thanks, Molekh, for the tip about regional usage of "stare"; things like this, Duo doesn't tell us. :))
Thanks to you! I can better understand now what you two meant.
Also, a clarification about my tip: I was just referring as "stare" used in statements like "Where are you?" which should be "Dove sei?" but as I told you in Rome they generally say "Dove stai?". There are, though, some instances where "stare" and "essere" overlaps, but it's not something to worry about to be honest. Obviously the Italian present continuous keeps the verb "stare", that's the rule.
I'm just saying this because I think my previous comment is a bit ambiguous.