Nah she's established enough on YouTube and has consistent enough noombers and watch time that her stuff gets spoonfed to people in recommendations, which is more valuable than per-game interest on Twitch since a lot of her streams aren't gameplay-related in the first place. Speaking strictly numbers-wise a not-insignificant portion of the watch time almost definitely comes from the live viewers in the moment rather than on-demand viewers, so moving "bigger" streams over to Twitch would cripple the overall channel performance, even if there are vod or highlight uploads posted in their place. It's not really worth gambling that, since the current system of higher-profile streams on YouTube and other shit on Twitch seems to work for her.
On a less objective, more speculative note, I can't see the kind of audience that "get" Pippa being the type of people who'd just lurk on Twitch looking for things to watch, Twitch has a much more zoomer-infested culture. I'm sure she'd get better audience retention from people who've been recommended her stream through YouTube's recommendations than Twitch's category system, which is a factor I feel like a lot of people don't give enough thought to when it comes to channel growth. Getting ten new viewers in a night who stick around for an hour is ultimately better for a streamer's performance on either platform than a hundred new viewers who clicked on the stream because they're playing a new release, didn't immediately hear a meme on TTS or see a Subway Surfers PiP, and closed the tab because their ADHD zoomoid brain got bored. I don't deny there's plenty of success stories one could point to on Twitch, but knowing your potential audience and where they're likely to be is important too. You need to go to them as much as recommendation algorithms need to bring them to you.
