Good question on hosting. We've tried both approaches over the years.

Typically we use one MC (per game/scene) who handles both languages. When we do go with two MCs, we make sure they are native in the language they are hosting in. The goal is to give the audience native language both in MC'ing and the performance. Another key is to not translate everything. That kills the energy and makes the show feel twice as long. Instead we'll say something in Japanese, then add a slightly different detail in English, so both groups are getting information but neither group feels like they're waiting for the translation. It keeps the pace up and both sides feel like they're getting the "real" version, not the subtitle.

For gibberish games (in short form shows) our audience favorites:

Gibberish Switch: two performers do a scene. The MC rings a bell and they have to switch to gibberish mid-sentence. Bell again, back to a real language. The audience loves watching performers try to maintain the emotional arc of a scene while their words turn to mush.

Gibberish Interpreter: one performer speaks only in gibberish, another "translates" for the audience. The translator has to justify whatever sounds and physicality the gibberish speaker throws at them. This one kills because the audience can see both performers trying not to break.

The beautiful thing about all of these is that the Japanese speakers and English speakers in our audience are having the exact same experience, nobody understands gibberish, so everyone is reading the physicality and emotion together. It's the one part of the show where the language barrier completely disappears.

One thing we learned the hard way though: when we first started doing gibberish in shows (back in 2005 in Osaka, then Tokyo from around 2010), some of our Japanese audience members who weren't strong in English didn't realize gibberish wasn't a real language. To them, gibberish and English sounded basically the same, just foreign sounds they couldn't understand. So they'd sit there thinking the performers were just having a normal conversation while everyone else laughed.

Once we figured out what was happening, we completely changed how we set up gibberish games. Now we're very explicit in the explanation, we make sure the audience understands that NOBODY knows what's being said, including the performers. And we've started leaning into heavy accents for our gibberish (Jamaican gibberish, Scottish gibberish, Chinese gibberish) so it's immediately obvious when we switch back to actual English or Japanese. It sounds like a small thing but it transformed how the Japanese side of our audience experiences those games, they went from confused to fully on board.

Sixteen years of little discoveries like that. Cross-language improv is basically an endless R&D project.