You could also of course try directly connecting the symbols to plausible translations - for instance, the antepenultimate letter of the first line of the first inscription doesn't appear elsewhere in the inscription, so is that also true of a letter in the supposed translation?
As far as letters go, this doesn't seem to be the case for the stated translation. I thought it might be instead one of the 'th' sounds, but the hard 'th' of 'thus' shows up again in 'this' in the last line and the soft 'th' shows up in 'the' in the second line. This is pretty solid evidence that the translation given in the movie isn't literal (the total character counts also don't match up, so there's that - it could still be syllable-based like katakana though).
In one of the previous attempts, I assigned each rune an english letter in order of their first appearance for ciphering purposes (and this also allows me to do letter frequency analysis pretty easily). This ends up with this ciphertext:
ABCDEFAFGHAIGC
JFGEKELKEMJFEBF
OKMJBHHAKLPEKLJBA
OQHERJKFCLSAQHKFO
KHNTHUEBXXFMFXFXKHLOLBEML
VJSHMJHWFBFUFSFOJDHCFBHSH
WAOJBYHAHXXXXXXHHBOSS
XBIZHXXXXXXXXEOFX
(X is a placeholder for illegible characters - while I'm fairly sure it's not just a crack in the stone, it's difficult to tell which character it might actually be).
The frequency analysis stats for the first, second and overall runesets looks like this:
From this, it looks like F is the most likely character to translate to 'E' if this is English (unless you think it's likely that E is way less common in the first set, in which case it'd be H?) If F=E, then the second set has a very curious-looking string of E-E-E-E in the second row, with each dash being a different letter (although this will be true for any F=, so I'm not sure what this means). H=E seems to look more 'realistic', with a few EE's here and there but overall even spacing. H=L would be most likely according to the most common bigram of LL, but EE or TT aren't too far behind.
I also reached out to the author of the translation page in my last post (this one), and they revealed they were able to decipher most of the languages by using the keyword 'Pokemon' - because it has two o's in a very specific spacing, they were able to fish it out of otherwise undecipherable text (however, they had quite a lot of ciphertext to work with, whereas I only have these two examples). To try and find this, I searched for N-grams 5 characters long with the same first and last letter (either 'OKEMO' or 'OMEKO' depending on whether it's forwards or backwards), and managed to find quite a few:
(first set)
AFGHA (invalid)
GHAIG (possible?)
LPEKL (invalid)
KLPEK (invalid)
EMJFE (possible?)
(second set)
HCFBH (possible?)
LBEML (possible?)
JSHMJ (invalid)
I tested these both forwards and backwards to see if 'Pokemon' could be spelled out. However, none of these give immediately visible solutions (and neither does the same approach for the second set), and thus the search continues. It's still possible that the keyword is in katakana or some other Japanese solution, but as you mentioned, I'd have to learn Japanese before I even attempted to tackle that. I'd hazard a guess that the keyword, if there is one, is either 'Pokemon,' 'Michina,' (the setting of the movie) or 'Arceus' (the antagonist referenced in the tablet's 'translation'), as these would be the most expected unique words to be on these tablets. Of these, Michina has one possible instance (OFBEFJM or JFBEFOK), and Arceus (a six-letter nonrepeating string) could be just about anywhere. There's also the problem that the keyword could be hidden somewhere in the X sections...