Sean hasn't yet succeeded dumping HD388xx electronically. He's built Tatsuyuki Sato's dumper*. But it appears that one only works for HD44801 by design, before dumping it checks if the factory testrom matches.

*: this thing, Team Europe made a blogpost about it https://team-europe.blogspot.com/2020/04/dumping-mcu-from-1986-hmcs40-alpha-8505.html