Ryukyu 1/2 Shu: real or fake?

I recently got this Ryukyu 1/2 Shu coin, and something is off about it. The text differs from the typical seal script used on these coins, with characters or parts of characters being more rounded. The only information I’ve managed to find on this has been this page on zeno.ru (https://www.zeno.ru/showphoto.php?photo=277523) with information that a coin with this design was apparently created as a rare trial issue, but that fakes exist. I compared mine to the drawing of the real one and the photos of the fake one, and mine seems to match the real one more, as well as looking more aged, like something from the 1860s rather than the 1970s, but with information on these trial pieces being hard to come by in English, I’m worried I can’t be sure. The big issue for me is the lack of the “サ” mark on the side, which is standard on the regular issues, but it could be that I’m just not seeing it or that marks like that weren’t made for trial coins. I’ve attached photos of both sides as well as the rim where the mark usually is. I’m personally somewhat confident this is legitimate, but I feel like I need some input from people more familiar with Ryukyuan coinage before I can be certain. ?

Hello

On the Zeno pics the Bao ( caracter of  the left ) is round on the original and the copy

but it seems that in yours the Bao is square…

Is it the picture ? Maybe you can see more clearely with coin in hand

gros

Hello

 

On the Zeno pics the Bao ( caracter of  the left ) is round on the original and the copy

but it seems that in yours the Bao is square…

Is it the picture ? Maybe you can see more clearely with coin in hand

It’s a bit hard to tell, the whole coin is fairly worn, but it does look a bit more squarish than the Zeno pictures, if I had to say one way or the other

Have you tried boiling it for a while it won't damage it and you will see what happens to the patina

If patina is real it will not change anything on it and no damage

gros

Have you tried boiling it for a while it won't damage it and you will see what happens to the patina

If patina is real it will not change anything on it and no damage

I trid