Polybius cipher

I am not an encryption expert by any means, but Polybius cipher as I understand unless is in the basic form requires a key to read it, it takes a cipher expert to break it quickly.

So what was in the movie has to be the basic form, and why would they put it in the basic form if the purpose was to encrypt it? Also if it is in the basic form then any idiot could read it by checking a standard reference tablet.

And Polybius ciphered text is in numbers like: 14 13 34 14 15 35 34 31 54 12 24 45 43 ..., even in Greek numbers it should look like this: https://mathworld.wolfram.com/GreekNumerals.html and that is not what was on the tablet.

If anyone is interested here is more information on Polybius cipher: https://www.dcode.fr/polybius-cipher

The more difficult part is probably the ancient Greek after translated (it certainly wasn't going to be in English), which should likely take an archaeologist, historian or linguist to translate, but it seems they both know ancient Greek.

Even Helena was very familiar with the cipher, what her father taught her should be in western digits and English instead of ancient Greek, I don't think any father was that cruel. If she studied archaeology and was well educated, then why became a thief?

From the look of ciphered text on the tablet, it is probably more likely Linear B, which is an early form of Greek writing: http://the-history-girls.blogspot.com/2012/11/cryptography-and-linear-b.html