Nothing egregious, really. I think Beaver Falls certainly could've warranted an F4 rating, and potentially in a few different areas. Actually surprised it didn't. Tionesta produced some really impressive contextual damage, but nothing I've found that'd clearly suggest F5. Same for Atlantic-Cherrytree. Neither hit very many structures when they were at their most intense, and even fewer structures were directly in the core of the path. I wouldn't be shocked if one or both reached that intensity at some point, though.
Moshannon's even trickier because there was
literally almost nothing substantial in most of its path. Lots of trees obviously, but even then it's hard to get really high-end tree damage in a forest that thick. Some summer/hunting cabins were destroyed but they weren't exactly well-built, and the PermaGrain facility wasn't really struck directly. The vast majority of the significant structural damage was near the beginning of the path, south of Penfield, which is before it really exploded.
The Johnstown, OH F3 is another underrated candidate, and one that I don't think most people know much about.
Possibly Saegertown-Centerville as well, but I'm still working on researching that so I'm only basing that on like two properties so far.
Oh! And while I don't necessarily think either was an F5 candidate, both the Barrie and Grand Valley F4s appear to have been more impressive than I'd always assumed before starting my research. Barrie was very likely the stronger of the two, but Grand Valley seems to be largely overshadowed. The thing was on the ground for 72 miles, yet the info/photos most people encounter come almost exclusively from the immediate GV area. It produced some pretty intense damage just based on what I've been able to dig up so far, particularly further east along the path.
For example, this home just south of Tottenham was reportedly "blown away" (except for the toilet) and scattered far downstream.
Obviously can't tell much about the construction here, and the tree in the background being only lightly damaged raises some questions, but the tornado was also quite narrow through this area. Probably not a case of a really well-anchored home being swept away, but even doing this to a home of more modest construction is fairly significant. Not far from this area, the tornado also tossed a combine roughly half a mile and apparently tore it up pretty good. Trying to find out what kind to get an idea of the weight, but figure several tons.