If you are using a Prius-compatible battery pack from a different vehicle e.g. rav4 ev or nx450h+ etc., then perhaps you should consider the corresponding parts for a charging system from that other vehicle rather than a Prius PHV charging system? You've probably thought of this? Perhaps the software control from the Prius is going to govern it and that's why you'd like Japanese CHAdeMO settings for software tuning? Also, the US is using Type 2 CCS connectors (I think?) rather than CHAdeMO for fast DC charging - since I have CHAdeMO will there be significant differences to be considered?