I think the twins' behaviour are pretty adult-like. What's their age at the moment, not only are they acting calm, they're actually following along with the plot he revealed. He didn't even put it in baby language, it's all worded as "I'll ruin the image of the royal family by making a public spectacle of the deaths of two illegitimate children from that family, thus proving they aren't infallible" rather than "empire go boom when you go byebye".
I have more issues with the "proving the royal blood isn't infallible by killing two known diluted versions of it, which was why they were illegitimate to begin with" loophole.
Anyway, thanks for the translations, and I'm hoping for more chapter updates because I just realised previous chaps the mother said she isn't human so are the kids illegitimate because daddy mated with a non-human or something??