I’m waiting for my hot glue gun to become, well hot, so I guess I should explain how Henry is accidentally learning Russian (This is based off of me for the past two years accidentally learning Hindi).
Basically I think Watts would read a ton of Russian books from a weird bookstore or whatever that just has Russian books for some reason. Anyways Watts reads the books at work when he has nothing else to do, and George is very instersted in the books (he mainly just likes it when Watts talks about something other than work) and Watts will explain what happened in every chapter to George after he finishes a chapter. Now for where Henry fits in, basically Henry will get distracted by the sound of the flipping pages so he looks over to them and his mind will be like “haha not English” (as your mind does), and at frist he doesn’t try to figure out what’s being said, but after enough time if he’s remembered enough of the pages he saw and hears what Watts says about each chapter, he starts to piece things together. He doesn’t really realize he’s been doing this becuase it would’ve been a gradual thing, and he probably figures out he does this if Watts was gone for a day and Murdoch needed him to translate a paper but Henry can do it just very choppy, then again Russian itself can be a choppy language sometimes. Repeating word probably would be a big help to Henry too.