Google Translate is a beast. It doesn't translate Traditional Chinese to English well AT ALL (but that's for another forum). I have found the Japanese translates enough to interpret the instructions when combined with the pictures for MP figures.
I don't know what the logic is behind not having "local language" instructions. I would have to translate either way though unless English was included. Admittedly all the MP's I've ever purchased are from Tak Tomy cases and the boxes inside generally aren't double (or triple) taped like the Hasbro direct stuff (eg Platinum Editions). Perhaps the distribution process is different or the cost to add the extra paper isn't justified as locals would just source from Japan given the pricing. I often wonder if the coins are produced to give the local suppliers a sweetener to entice people in Asia (but outside Japan) to buy local.
Not all local HK suppliers get the coins though as some bypass Hasbro HK and source direct from Japan so if you are buying MP's and you WANT the coin you have to check if stores include it before buying/pre ordering.