Last year we did the Polynesian Luau with Mickey and Friends (food was horrible) and the main parts were in English!
Duffy show at Cape Cod is a continuous series of short acts that runs all day. During peak hours CMs show you to your seats, in lower volume, you choose your own seat. Nobody can enter until entire party has the food/bevs all together (eg no saving seats). I'm sure shows we saw at the end of the day were in English (I could be wrong, it was a very simple storyline about Duffy's creation).
Last character meal we went to was Woody's Roundup at the Diamond Horseshoe. Lots of English banter and songs. Free bandana! I do remember some Japanese but our server spoke in English to us about drinks. Food is served family style and is refilled if requested.
Overall we did not have any issues with language at either park accept the show next to Sinbad's Voyage had run out of the English translator machines during our show but we had been previously so had seen it before.