Is that directory named
or is it named
Due to the link format with the underline that cannot be seen on your screenshot.
If it's the first case then that is your error - for all HTML5-based games (especially if they go to different operating systems) all filepath and all filenames have to follow networking rules. That means means absolutely no spaces (and several other rules like only latin letters or arabic numbers and very few other signs)
I think it's not problem, the game run well in both PC and other Android version except Android 5 because of this bug. Seem like Android 5 doesn't use document.fonts...
Beside, just like rpg_core, the name is android_asset
Not quite sure if this is your problem but I know from testing that some fonts just won't work on Android. You could try testing with a different font and see what happens. Usually that problem results in the game just failing to load, though - not an "undefined is not a function" error.