had the same problem with my pinbot.
different mpu though.
after i installed the jumper i could actually read the words.

with system 11 i found even if i changed the language in the settingsto english (without the jumper installed) the custom message would still come up in german, but when i replaced the jumper the custom message would come up in english.

i dont know if its the same with the mpu in WH 20 
 
when you had the old roms in was it in english? and was the jumper installed?