Excellent remark @DPardess! If you want to FORETELL the future, you would say something like, "She will find my uncle" which makes me think the uncle is unable to move and therefore will inevitably be found. But, if you want to FORECAST the future, you would say something like, "She will have found my uncle--unless he literally disappeared!" There also exists such a thing as FORESHADOWING, which would be like saying, "Let's find him."
I was thinking the same thing, that this should translate as "she must have found my uncle" or "I wonder if she has found my uncle" or something of the sort to be the most accurate in terms of what a native speaker would most likely mean if they were to say this exact sentence.
Well, usually (in my American Standard dialect anyway) we use contractions in the future or future perfect tense: "She'll have found" and this sentence is a bit unnatural without any context: "She'll have found my uncle by then." However regular future tense would also be valid in most contexts I can think of right now: "She'll find him before we get there."