I mean, no?

You can see no vertical protrusions of the vertebrae so there’s going to be A: vertical movement as muscles can best attach to pull up/down. And B: a likely flat structural rail with how wide the horizontal protrusions are. C: nothing sharp or heavily weighted at the end so likely not a huge weaponised tail like a thagomizer. So… you’ve got a probably flat tail, than can slam down on stuff.

Now figuring out WHY it was like that would require being able to find fossils around rivers and being able to tell those rivers had dams or something cuz idk how they would figure out exactly how they use their tails but… yeah you can figure the general shape fine based on vertebrae anatomy which leads to (possible)muscle anatomy. Some bones don’t function the way they look and can throw stuff off. Someone else already mentioned stuff like air sacks in birds and such that would really throw off anatomy based on bone and assumed muscular structure from where bones could have attached muscles.

Pretty much. You can factually tell that a lot of something was going on with all of those delicious muscle hooks on such a small frame, but a flat paddle mightn’t be their first thought. Really depends on who sees it first, but they'd eventually get at least close. Just give it a few years of screaming. Yes, both external and internal.