I don't think I can't help here, but I did spend a good 2 hours looking into this.
As far as I can tell the engine is cocos2djs ver 3.15. And most of the non-engine game files are encrypted.
And what little I looked into that, there's possibly a decryption tool that can open these files up:
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The documentation there seems to suggest that the game files are encrypted with a key signature which can be found in the main APK, but since this is Windows and not Android.. I'm wondering if the 'key' reference found in:
Resources/Data/info.json might be it.
As a Windows user however, I don't have a Python+Linux development environment (OR VM) and I'm not about to waste a day setting one up, but it looks like that's the first step forward.
Assuming that's successful, you'll presumably have access to the Japanese language files which you could then run through Google Translate and get a baseline translation started. There's not a lot of game files in here in general... but the file 'project.json' looks like one of the largest text files in the game folders, so that's
probably the file you want?