Linguistic Focus is a lovely tool, but it seems to be a bit glitchy. It doesn’t seem to see compound adjectives at all, and is iffy about others: “frost-bitten grey streets” - only “grey” shows as an adjective; “an anal, clinical building” - only “clinical”; “a rickety wrought-iron gate” - neither “rickety” nor “wrought-iron” comes up as an adjective. What’s going on?
With the exception of the direct-speech option, these tools are all provided by the Mac, as part of the text editor. My guess is that they had a system for this already built for the grammar checker, and figured it would nice and easy to make it available to other developers like us. Whatever the case, expect it to be about as accurate as grammar checking. 
Thanks, Amber. I’m sending an email to Support about this (don’t want to post a screenshot of someone else’s work). It should be a really useful tool especially for beginning writers. Perhaps your excellent coders can sharpen it up.
Like I say, the only thing we ourselves can improve is the direct-speech detection (and we have, we added em-dash style dialogue detection a while back). Everything else is as difficult/impossible to change as… well like spell check itself. It’s something the Mac is doing at our behest, like printing or looking up a word in the Oxford dictionary.