(I’m assuming a definition as per Meriam-Webster: “awkward or difficult to handle because of many small parts or details”.)
I can see folks thinking there are a lot of things going on, a lot of things to remember, that might or might not trigger. I'd say it's a little fiddly, yeah.
Is it the 17th most fiddly game in the entire BGG database? I have no idea, but I doubt it.
Now, is it one of the games with a lot of comments? Well, the only other game on the "fiddly" list that beat it was Loius XIV, and it was 1330 to 1339, and the next closest is at 675, so I'd say yeah. And I think that makes a big difference.
My biggest issue with these ratings is (as stated) it doesn't differentiate good or bad uses. If someone says "Sentinels isn't as fiddly as X", it counts. That's not useful or even interesting to me, primarily because people can get into an argument about it, which will ratchet up the count as responses quote and contradict the folks saying it is fiddly. On games with fewer comments, those "fiddly" posts probably won't get much response, if any, so there are fewer instances.
I suppose it's an interesting conversation starter, but it's not very scientific. 
There are certainly more games more "fiddly" than SotM. There's certainly a lot of leeway as far as how these words can be used in the comments. I think Sentinels is very straightforward as far as conflict resolution goes, and there arent a lot of parts to it, just different ongoings to keep track of.
Is GSF on that list? Sure that's more fiddly than SotM.
That's exactly the kind of thing I'm talking about. We know there are things more fiddly, but folks haven't commented on it so it doesn't come up. 
But at the same time, it's all individual opinion, so… 
Fiddly.
Now there's another comment to boost the ratings.
Discussions of whether or not this game is fiddly probably drive the rating more than anything.
If we have a 35 comment argument about whether the game is somewhat fiddly or not fiddly at all we boost the ratings.
We have had a lot of those type of arguments.
So Is SotM fiddly? That list can't determine that with it's methodology.
What it can determine is that Sentinels ranks 17th among gaming communities on the frequency of discussions using the word fiddly.
So yeah, we talk about it a lot, which pretty much means the game is fiddly. But not more or less so than others.
Sentinels is on the fiddly side of accessible. As in it is very accessible, and therefore is played by people who find it fiddly, and play it anyway, where as GSF just scares those people right out of the room.
I hate the word "Fiddly". Loath it. It is a largely nebulous term in tabletop, thrown around so offten and carelessly that it has ceased to be meaningfull in any capacity whatsoever.
Sentinels also made the list for "Replay."
Whiel SotM has a lot of moving parts, the game is robust enough that it doesn't fall apart if you forget an end of turn action, for example. It's complicated enough that it probably feels fiddly, but not so fiddly that falls apart.
For comparison, I'm pretty sure that SotM is in the top five, through the methodology of this search, for "Rebottaro".
Fiddly and richness often go together, and I don't know how much you could give up of the games richness to decrease the fiddliness.
Thanks for catching that! I didn't even know there were multiple pages to it.
#18, huh. Interesting… Same comments are still valid, of course, even though this is a positive one.
(Direct link, for those interested.)