According to that bug report, you've only got one failing test. That test is checking for whether two events happening inside the same directory were coalesced into one. However, the File System Events Programming Guide says (emphasis mine):

... the file system events daemon also coalesces multiple notifications on a given directory if they occur in a short period of time. You will always receive at least one notification ... If an event in a directory occurs at about the same time as one or more events in a subdirectory of that directory, the events may be coalesced into a single event.

It seems to me that the test is making an assumption it shouldn't, and it's probably safe to force install the module.

Ok, cool. But any idea on why it might install fine on an older OS and not on Catalina? I know next to nothing about lower level FS stuff.

$PM = "Perl Monk's";
$MCF = "Most Clueless Friar Abbot Bishop Pontiff Deacon Curate Priest Vicar";
$nysus = $PM . ' ' . $MCF;
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But any idea on why it might install fine on an older OS and not on Catalina?

Nope, sorry. There is a possibility that something changed between those OS versions, but the specs document is pretty clear that the behavior causing the test failure is allowed, so unless I've missed something I still think the test is the problem here.