The phrase "appears to be frustrated" is correct and usable in written English.
You can use it when describing someone's emotional state or reaction, often in a context where their frustration is not explicitly stated but inferred from their behavior or expressions.
Example: "During the meeting, she appears to be frustrated with the lack of progress on the project."
Alternatives: "seems to be annoyed" or "looks to be upset."
As Mr. Goel leaked internal goings-on at Intel, he also appeared to be frustrated with his career.
Several justices seemed inclined to find a way to help Mr. Maples and appeared to be frustrated by the conduct of Alabama officials.
But it was in the run up to half-time with the home side two goals to the good that he was in conversation with an assistant referee after appearing to be frustrated by comments made by supporters behind the goal.
At one point Blum appeared to be frustrated with the audience, which repeatedly booed and jeered his answers, telling an aide that "nobody's listening".
And he appears to be genuinely frustrated by the British government's whole approach to Europe.
Developers are frustrated over what appears to be an issue with corrupt app store binaries being served by Apple, which is leading otherwise functional iOS and Mac applications to immediately crash upon launch.
His page appears to be that of a sexually frustrated older man, the kind of desperate dad who flirts with his daughter's teenage friends.
Brandon DeMelle of DeSmogBlog, frustrated with what appears to be a pretty limp effort, began his post on the end of the investigation this way: "Our Priority is You," reads the tagline of the Norfolk Constabulary.
Investigators from the Justice Department, who at first believed Martha Stewart's explanation of the timing of her sale of ImClone shares, have grown frustrated at what appears to be holes in the explanation, a person briefed on the matter said.
[C2.] Committee Is Frustrated by Stewart Investigators who at first believed Martha Stewart's explanation of the timing of her sale of ImClone shares, have grown frustrated at what appears to be holes in the explanation, a person briefed on the matter said.
